feat(email): add ImapProvider (generic IMAP for unsupported providers)

b3 of the multi-provider email roadmap. Adds ImapConnection model + table
(reconciler pattern, SQLite+MySQL), ImapService (MailKit-backed IMAP client),
ImapProvider implementing the existing IEmailProvider contract unchanged,
and ImapController for credential-based connect (no OAuth — user supplies
host/username/password directly, verified by a live connect before storage).

Scope, documented inline with ponytail: comments:
- INBOX only, no multi-folder support.
- Thread grouping approximates the References/In-Reply-To chain root rather
  than the IMAP THREAD extension, which not every server implements.
- External message ids are IMAP UIDs, scoped to the connection's current
  UIDVALIDITY.

Security: ran the security-audit skill against this diff (credential
handling + arbitrary-host connect is exactly the class of change the
standing security gate exists for). Found and fixed a real SSRF: the
connect endpoint let an authenticated user point the server at an
arbitrary host:port with no internal-range check, and connect-vs-auth
failure was distinguishable to the caller -- together a working oracle to
fingerprint internal services (loopback/RFC1918/link-local/cloud metadata)
from the server's network position. Fixed with EnsureHostIsExternalAsync
(DNS-resolve + reject internal ranges, re-checked on every reconnect to
close the DNS-rebinding gap) and a single generic failure message that no
longer distinguishes connect vs auth failure. 7 regression tests added.

Dependency: MailKit 4.17.0 (MIT license) on JobTrackerBackend.csproj --
stdlib has no IMAP client; hand-rolling IMAP4rev1 (TLS, SASL, MIME parsing)
would be a large, security-sensitive protocol implementation nobody asked
for, so this is the correct dependency, not a stdlib substitute.

168/168 green (161 existing + 7 new SSRF regression tests; the earlier
14 IMAP feature tests are included in the 161).

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

JobTrackerApi/Controllers/ImapController.cs

@@ -0,0 +1,96 @@
+using System.Security.Claims;
+using JobTrackerApi.Services;
+using Microsoft.AspNetCore.Authorization;
+using Microsoft.AspNetCore.Mvc;
+
+namespace JobTrackerApi.Controllers;
+
+/// <summary>
+/// Generic IMAP connection lifecycle for mailboxes with no dedicated OAuth provider. Unlike
+/// Gmail/Microsoft, there's no OAuth redirect — the caller submits host/username/password once,
+/// <see cref="IImapService"/> verifies them by connecting, then encrypts and stores them.
+/// </summary>
+[ApiController]
+[Route("api/imap")]
+[Authorize]
+public sealed class ImapController : ControllerBase
+{
+    private readonly IImapService _imap;
+
+    public ImapController(IImapService imap)
+    {
+        _imap = imap;
+    }
+
+    public sealed record ImapConnectRequest(string Host, int Port, bool UseSsl, string Username, string Password);
+
+    public sealed record ImapConnectionStatusDto(
+        bool Connected,
+        string? Host,
+        int? Port,
+        bool? UseSsl,
+        string? Username,
+        DateTimeOffset? ConnectedAt,
+        DateTimeOffset? LastSyncedAt,
+        DateTimeOffset? LastSyncAttemptedAt,
+        DateTimeOffset? LastSyncSucceededAt,
+        string? LastSyncMode,
+        string? LastSyncSource,
+        string? LastSyncStatus,
+        string? LastSyncError);
+
+    [HttpGet("status")]
+    public async Task<ActionResult<ImapConnectionStatusDto>> Status(CancellationToken cancellationToken)
+    {
+        var ownerUserId = GetRequiredOwnerUserId();
+        var connection = await _imap.GetConnectionAsync(ownerUserId, cancellationToken);
+        return Ok(new ImapConnectionStatusDto(
+            connection is not null,
+            connection?.Host,
+            connection?.Port,
+            connection?.UseSsl,
+            connection?.Username,
+            connection?.ConnectedAt,
+            connection?.LastSyncedAt,
+            connection?.LastSyncAttemptedAt,
+            connection?.LastSyncSucceededAt,
+            connection?.LastSyncMode,
+            connection?.LastSyncSource,
+            connection?.LastSyncStatus,
+            connection?.LastSyncError));
+    }
+
+    [HttpPost("connect")]
+    public async Task<IActionResult> Connect([FromBody] ImapConnectRequest request, CancellationToken cancellationToken)
+    {
+        if (string.IsNullOrWhiteSpace(request.Host)) return BadRequest("Host is required.");
+        if (request.Port <= 0 || request.Port > 65535) return BadRequest("Valid port is required.");
+        if (string.IsNullOrWhiteSpace(request.Username)) return BadRequest("Username is required.");
+        if (string.IsNullOrWhiteSpace(request.Password)) return BadRequest("Password is required.");
+
+        var ownerUserId = GetRequiredOwnerUserId();
+        try
+        {
+            var result = await _imap.ConnectAsync(ownerUserId, request.Host, request.Port, request.UseSsl, request.Username, request.Password, cancellationToken);
+            return Ok(new { username = result.Username });
+        }
+        catch (InvalidOperationException ex)
+        {
+            return BadRequest(ex.Message);
+        }
+    }
+
+    [HttpDelete("connection")]
+    public async Task<IActionResult> Disconnect(CancellationToken cancellationToken)
+    {
+        var ownerUserId = GetRequiredOwnerUserId();
+        await _imap.DisconnectAsync(ownerUserId, cancellationToken);
+        return NoContent();
+    }
+
+    private string GetRequiredOwnerUserId()
+    {
+        return User.FindFirstValue(ClaimTypes.NameIdentifier) ?? User.FindFirstValue("sub")
+            ?? throw new InvalidOperationException("Authenticated user id is missing.");
+    }
+}

JobTrackerApi/Program.cs

@@ -166,10 +166,12 @@ builder.Services.AddScoped<IGmailOAuthService, GmailOAuthService>();
 builder.Services.AddSingleton<IGmailJobMatchingService, GmailJobMatchingService>();
 builder.Services.AddSingleton<IGmailCorrespondenceEnrichmentService, NoOpGmailCorrespondenceEnrichmentService>();
 builder.Services.AddScoped<IMicrosoftGraphOAuthService, MicrosoftGraphOAuthService>();
+builder.Services.AddScoped<IImapService, ImapService>();
 
-// Provider-neutral email seam (multi-provider: Gmail + Microsoft Graph today; IMAP / manual next).
+// Provider-neutral email seam (multi-provider: Gmail + Microsoft Graph + IMAP today; manual next).
 builder.Services.AddScoped<JobTrackerApi.Services.EmailProviders.IEmailProvider, JobTrackerApi.Services.EmailProviders.GmailProvider>();
 builder.Services.AddScoped<JobTrackerApi.Services.EmailProviders.IEmailProvider, JobTrackerApi.Services.EmailProviders.MicrosoftGraphProvider>();
+builder.Services.AddScoped<JobTrackerApi.Services.EmailProviders.IEmailProvider, JobTrackerApi.Services.EmailProviders.ImapProvider>();
 builder.Services.AddScoped<JobTrackerApi.Services.EmailProviders.IEmailProviderRegistry, JobTrackerApi.Services.EmailProviders.EmailProviderRegistry>();
 
 builder.Services.AddIdentityCore<ApplicationUser>(options =>

JobTrackerApi/Services/EmailProviders/ImapProvider.cs

@@ -0,0 +1,63 @@
+using JobTrackerApi.Services;
+
+namespace JobTrackerApi.Services.EmailProviders
+{
+    /// <summary>
+    /// Generic IMAP implementation of <see cref="IEmailProvider"/> for mailboxes with no
+    /// dedicated OAuth provider. Adapts <see cref="IImapService"/> to the provider-neutral
+    /// contract, mapping IMAP DTOs to the neutral shapes.
+    /// </summary>
+    public sealed class ImapProvider : IEmailProvider
+    {
+        private readonly IImapService _imap;
+
+        public ImapProvider(IImapService imap)
+        {
+            _imap = imap;
+        }
+
+        public string ProviderKey => "imap";
+
+        public async Task<EmailConnectionInfo?> GetConnectionAsync(string ownerUserId, CancellationToken cancellationToken)
+        {
+            var connection = await _imap.GetConnectionAsync(ownerUserId, cancellationToken);
+            return connection is null ? null : new EmailConnectionInfo("imap", connection.Username ?? "");
+        }
+
+        public async Task<IReadOnlyList<EmailMessageSummary>> SearchAsync(string ownerUserId, string? query, int maxResults, CancellationToken cancellationToken)
+        {
+            var messages = await _imap.ListMessagesAsync(ownerUserId, query, maxResults, cancellationToken);
+            return messages.Select(ToSummary).ToList();
+        }
+
+        public async Task<IReadOnlyList<EmailMessageSummary>> ListThreadMessagesAsync(string ownerUserId, string threadId, CancellationToken cancellationToken)
+        {
+            var messages = await _imap.ListThreadMessagesAsync(ownerUserId, threadId, cancellationToken);
+            return messages.Select(ToSummary).ToList();
+        }
+
+        public async Task<EmailMessageDetail> GetMessageAsync(string ownerUserId, string messageId, CancellationToken cancellationToken)
+        {
+            var detail = await _imap.GetMessageAsync(ownerUserId, messageId, cancellationToken);
+            var attachments = detail.Attachments
+                .Select(a => new EmailAttachmentRef(a.FileName, a.MimeType, a.SizeBytes, a.ContentId, a.Inline))
+                .ToList();
+
+            return new EmailMessageDetail(
+                detail.Id,
+                detail.ThreadKey,
+                detail.Subject,
+                detail.From,
+                detail.To,
+                detail.Date,
+                detail.Snippet,
+                detail.BodyText,
+                detail.BodyHtml,
+                detail.Labels,
+                attachments);
+        }
+
+        private static EmailMessageSummary ToSummary(ImapMessageSummary m)
+            => new(m.Id, m.ThreadKey, m.Subject, m.From, m.To, m.Date, m.Snippet);
+    }
+}

JobTrackerApi/Services/ImapService.cs

@@ -0,0 +1,345 @@
+using JobTrackerApi.Data;
+using JobTrackerApi.Models;
+using MailKit;
+using MailKit.Net.Imap;
+using MailKit.Search;
+using Microsoft.AspNetCore.DataProtection;
+using Microsoft.EntityFrameworkCore;
+using MimeKit;
+using System.Net;
+using System.Net.Sockets;
+using System.Security.Cryptography;
+
+namespace JobTrackerApi.Services;
+
+public interface IImapService
+{
+    Task<ImapConnectResult> ConnectAsync(string ownerUserId, string host, int port, bool useSsl, string username, string password, CancellationToken cancellationToken);
+    Task<ImapConnection?> GetConnectionAsync(string ownerUserId, CancellationToken cancellationToken);
+    Task DisconnectAsync(string ownerUserId, CancellationToken cancellationToken);
+    Task<IReadOnlyList<ImapMessageSummary>> ListMessagesAsync(string ownerUserId, string? query, int maxResults, CancellationToken cancellationToken);
+    Task<IReadOnlyList<ImapMessageSummary>> ListThreadMessagesAsync(string ownerUserId, string threadKey, CancellationToken cancellationToken);
+    Task<ImapMessageDetail> GetMessageAsync(string ownerUserId, string messageId, CancellationToken cancellationToken);
+}
+
+public sealed record ImapConnectResult(string Username);
+public sealed record ImapMessageSummary(string Id, string ThreadKey, string Subject, string From, string To, DateTimeOffset? Date, string Snippet);
+public sealed record ImapMessageAttachment(string? FileName, string? MimeType, long? SizeBytes, string? ContentId, bool Inline);
+public sealed record ImapMessageDetail(string Id, string ThreadKey, string Subject, string From, string To, DateTimeOffset? Date, string Snippet, string BodyText, string? BodyHtml, IReadOnlyList<string> Labels, IReadOnlyList<ImapMessageAttachment> Attachments);
+
+/// <summary>
+/// Generic IMAP mail access for "any provider not explicitly supported" (Gmail/Microsoft have
+/// their own OAuth-based providers). Auth is direct host/username/password rather than OAuth —
+/// there's no connect-url/callback dance, the caller submits credentials once and they're
+/// encrypted at rest the same way Gmail/Microsoft's refresh tokens are.
+///
+/// ponytail: scoped to INBOX only, and "thread" is approximated from the References/In-Reply-To
+/// headers (the root Message-Id) rather than the server-side IMAP THREAD extension, which not
+/// every provider implements. Good enough for "show me the other messages in this conversation";
+/// upgrade to THREAD/SORT if a target provider needs cross-folder or extension-grade threading.
+/// External message ids are "{UID}" scoped to INBOX under the connection's current UIDVALIDITY —
+/// they are not stable across a UIDVALIDITY change (rare: a full mailbox reset on the server).
+/// </summary>
+public sealed class ImapService : IImapService
+{
+    private const int ThreadScanWindow = 200;
+    private readonly JobTrackerContext _db;
+    private readonly IDataProtector _protector;
+
+    public ImapService(JobTrackerContext db, IDataProtectionProvider protectionProvider)
+    {
+        _db = db;
+        _protector = protectionProvider.CreateProtector("imap-credentials-v1");
+    }
+
+    public async Task<ImapConnectResult> ConnectAsync(string ownerUserId, string host, int port, bool useSsl, string username, string password, CancellationToken cancellationToken)
+    {
+        host = host.Trim();
+        username = username.Trim();
+        if (host.Length == 0) throw new InvalidOperationException("IMAP host is required.");
+        if (username.Length == 0) throw new InvalidOperationException("IMAP username is required.");
+        if (string.IsNullOrEmpty(password)) throw new InvalidOperationException("IMAP password is required.");
+
+        // Verify the credentials actually work before persisting them. Failure detail is
+        // intentionally generic (not the raw MailKit exception) so a "connect" attempt can't be
+        // used as a distinguishable oracle to fingerprint what's listening on a given host:port.
+        using (var client = new ImapClient())
+        {
+            try
+            {
+                await EnsureHostIsExternalAsync(host, cancellationToken);
+                await client.ConnectAsync(host, port, useSsl, cancellationToken);
+                await client.AuthenticateAsync(username, password, cancellationToken);
+            }
+            catch (Exception ex) when (ex is not OperationCanceledException)
+            {
+                throw new InvalidOperationException("Could not connect to that IMAP server with the given credentials. Check host, port, and password.");
+            }
+            finally
+            {
+                if (client.IsConnected)
+                {
+                    await client.DisconnectAsync(true, cancellationToken);
+                }
+            }
+        }
+
+        var existing = await _db.ImapConnections.FirstOrDefaultAsync(x => x.OwnerUserId == ownerUserId, cancellationToken);
+        if (existing is null)
+        {
+            existing = new ImapConnection { OwnerUserId = ownerUserId };
+            _db.ImapConnections.Add(existing);
+        }
+
+        existing.Host = host;
+        existing.Port = port;
+        existing.UseSsl = useSsl;
+        existing.Username = username;
+        existing.EncryptedPassword = _protector.Protect(password);
+        existing.ConnectedAt = DateTimeOffset.UtcNow;
+        existing.LastSyncStatus = "connected";
+        existing.LastSyncSource = "connect";
+        existing.LastSyncMode = "connect";
+        existing.LastSyncError = null;
+        existing.LastSyncAttemptedAt = DateTimeOffset.UtcNow;
+        existing.LastSyncSucceededAt = existing.LastSyncAttemptedAt;
+
+        await _db.SaveChangesAsync(cancellationToken);
+        return new ImapConnectResult(existing.Username);
+    }
+
+    public Task<ImapConnection?> GetConnectionAsync(string ownerUserId, CancellationToken cancellationToken)
+        => _db.ImapConnections.AsNoTracking().FirstOrDefaultAsync(x => x.OwnerUserId == ownerUserId, cancellationToken);
+
+    public async Task DisconnectAsync(string ownerUserId, CancellationToken cancellationToken)
+    {
+        var existing = await _db.ImapConnections.FirstOrDefaultAsync(x => x.OwnerUserId == ownerUserId, cancellationToken);
+        if (existing is null) return;
+        _db.ImapConnections.Remove(existing);
+        await _db.SaveChangesAsync(cancellationToken);
+    }
+
+    public async Task<IReadOnlyList<ImapMessageSummary>> ListMessagesAsync(string ownerUserId, string? query, int maxResults, CancellationToken cancellationToken)
+    {
+        maxResults = Math.Clamp(maxResults, 1, 25);
+        try
+        {
+            using var client = await OpenInboxAsync(ownerUserId, false, cancellationToken);
+            var searchQuery = string.IsNullOrWhiteSpace(query)
+                ? SearchQuery.All
+                : SearchQuery.SubjectContains(query.Trim()).Or(SearchQuery.FromContains(query.Trim())).Or(SearchQuery.BodyContains(query.Trim()));
+
+            var uids = await client.Inbox.SearchAsync(searchQuery, cancellationToken);
+            var window = uids.OrderByDescending(u => u.Id).Take(maxResults).ToList();
+            var summaries = await FetchSummariesAsync(client, window, cancellationToken);
+
+            await TouchSyncStateAsync(ownerUserId, "list-messages", string.IsNullOrWhiteSpace(query) ? "default-query" : "custom-query", true, null, cancellationToken);
+            return summaries;
+        }
+        catch (Exception ex)
+        {
+            await TouchSyncStateAsync(ownerUserId, "list-messages", string.IsNullOrWhiteSpace(query) ? "default-query" : "custom-query", false, ex.Message, cancellationToken);
+            throw;
+        }
+    }
+
+    public async Task<IReadOnlyList<ImapMessageSummary>> ListThreadMessagesAsync(string ownerUserId, string threadKey, CancellationToken cancellationToken)
+    {
+        if (string.IsNullOrWhiteSpace(threadKey))
+        {
+            return Array.Empty<ImapMessageSummary>();
+        }
+
+        try
+        {
+            using var client = await OpenInboxAsync(ownerUserId, false, cancellationToken);
+            var recentUids = (await client.Inbox.SearchAsync(SearchQuery.All, cancellationToken))
+                .OrderByDescending(u => u.Id)
+                .Take(ThreadScanWindow)
+                .ToList();
+
+            var items = await client.Inbox.FetchAsync(recentUids, MessageSummaryItems.Envelope | MessageSummaryItems.References | MessageSummaryItems.UniqueId, cancellationToken);
+            var matches = items.Where(item => ComputeThreadKey(item) == threadKey.Trim()).ToList();
+            var summaries = matches.Select(ToSummary).OrderBy(s => s.Date).ToList();
+
+            await TouchSyncStateAsync(ownerUserId, "thread-refresh", "reference-scan", true, null, cancellationToken);
+            return summaries;
+        }
+        catch (Exception ex)
+        {
+            await TouchSyncStateAsync(ownerUserId, "thread-refresh", "reference-scan", false, ex.Message, cancellationToken);
+            throw;
+        }
+    }
+
+    public async Task<ImapMessageDetail> GetMessageAsync(string ownerUserId, string messageId, CancellationToken cancellationToken)
+    {
+        try
+        {
+            using var client = await OpenInboxAsync(ownerUserId, false, cancellationToken);
+            var uid = ParseUid(messageId);
+
+            var summaryItems = await client.Inbox.FetchAsync(new[] { uid }, MessageSummaryItems.Envelope | MessageSummaryItems.References | MessageSummaryItems.UniqueId, cancellationToken);
+            var summary = summaryItems.FirstOrDefault() ?? throw new InvalidOperationException($"IMAP message {messageId} was not found.");
+
+            var mime = await client.Inbox.GetMessageAsync(uid, cancellationToken);
+            var bodyText = mime.TextBody ?? (mime.HtmlBody is null ? "" : StripHtml(mime.HtmlBody));
+            var attachments = mime.Attachments.Select(a => new ImapMessageAttachment(
+                a.ContentDisposition?.FileName ?? a.ContentType?.Name,
+                a.ContentType?.MimeType,
+                a is MimePart part ? part.Content?.Stream?.Length : null,
+                a.ContentId,
+                a.IsAttachment == false
+            )).ToList();
+
+            await TouchSyncStateAsync(ownerUserId, "message-detail", "imap-message", true, null, cancellationToken);
+            return new ImapMessageDetail(
+                messageId,
+                ComputeThreadKey(summary),
+                summary.Envelope?.Subject ?? "",
+                FormatAddresses(summary.Envelope?.From),
+                FormatAddresses(summary.Envelope?.To),
+                summary.Envelope?.Date,
+                bodyText.Length > 200 ? bodyText[..200] : bodyText,
+                bodyText.Trim(),
+                mime.HtmlBody,
+                Array.Empty<string>(),
+                attachments);
+        }
+        catch (Exception ex)
+        {
+            await TouchSyncStateAsync(ownerUserId, "message-detail", "imap-message", false, ex.Message, cancellationToken);
+            throw;
+        }
+    }
+
+    private static async Task<IReadOnlyList<ImapMessageSummary>> FetchSummariesAsync(ImapClient client, IList<UniqueId> uids, CancellationToken cancellationToken)
+    {
+        if (uids.Count == 0) return Array.Empty<ImapMessageSummary>();
+        var items = await client.Inbox.FetchAsync(uids, MessageSummaryItems.Envelope | MessageSummaryItems.References | MessageSummaryItems.UniqueId, cancellationToken);
+        return items.Select(ToSummary).ToList();
+    }
+
+    private static ImapMessageSummary ToSummary(IMessageSummary item) => new(
+        item.UniqueId.Id.ToString(),
+        ComputeThreadKey(item),
+        item.Envelope?.Subject ?? "",
+        FormatAddresses(item.Envelope?.From),
+        FormatAddresses(item.Envelope?.To),
+        item.Envelope?.Date,
+        "");
+
+    // The root Message-Id of the References chain, or this message's own Message-Id if it
+    // starts no chain — a stand-in "thread id" that works without the IMAP THREAD extension.
+    private static string ComputeThreadKey(IMessageSummary item)
+    {
+        if (item.References is { Count: > 0 })
+        {
+            return item.References[0];
+        }
+        return item.Envelope?.MessageId ?? item.UniqueId.Id.ToString();
+    }
+
+    private static string FormatAddresses(InternetAddressList? list)
+        => list is null ? "" : string.Join(", ", list.Mailboxes.Select(m => m.Address));
+
+    private static string StripHtml(string html)
+        => System.Text.RegularExpressions.Regex.Replace(html, "<[^>]+>", " ").Trim();
+
+    private static UniqueId ParseUid(string messageId)
+        => uint.TryParse(messageId, out var id) ? new UniqueId(id) : throw new InvalidOperationException($"Invalid IMAP message id: {messageId}");
+
+    private async Task<ImapClient> OpenInboxAsync(string ownerUserId, bool writable, CancellationToken cancellationToken)
+    {
+        var connection = await _db.ImapConnections.FirstOrDefaultAsync(x => x.OwnerUserId == ownerUserId, cancellationToken)
+            ?? throw new InvalidOperationException("IMAP is not connected for this account.");
+
+        string password;
+        try
+        {
+            password = _protector.Unprotect(connection.EncryptedPassword);
+        }
+        catch (CryptographicException)
+        {
+            throw new InvalidOperationException("Your stored IMAP connection can no longer be decrypted after a server key change. Disconnect and reconnect IMAP.");
+        }
+
+        await EnsureHostIsExternalAsync(connection.Host, cancellationToken);
+        var client = new ImapClient();
+        await client.ConnectAsync(connection.Host, connection.Port, connection.UseSsl, cancellationToken);
+        await client.AuthenticateAsync(connection.Username, password, cancellationToken);
+        await client.Inbox.OpenAsync(writable ? FolderAccess.ReadWrite : FolderAccess.ReadOnly, cancellationToken);
+        return client;
+    }
+
+    // SSRF guard: a user-supplied IMAP host resolves to an IP the server then opens a socket to.
+    // Without this check an authenticated user could point "their mailbox" at loopback, RFC1918/
+    // link-local ranges, or the cloud metadata address to probe internal infrastructure. Re-run on
+    // every connect (not just the initial one) so a DNS record that resolves externally at connect
+    // time can't be rebound internally for a later reconnect.
+    private static async Task EnsureHostIsExternalAsync(string host, CancellationToken cancellationToken)
+    {
+        IPAddress[] addresses;
+        try
+        {
+            addresses = await Dns.GetHostAddressesAsync(host, cancellationToken);
+        }
+        catch (SocketException)
+        {
+            throw new InvalidOperationException("Could not resolve that IMAP host.");
+        }
+
+        if (addresses.Length == 0 || addresses.Any(IsInternalAddress))
+        {
+            throw new InvalidOperationException("That IMAP host is not reachable.");
+        }
+    }
+
+    private static bool IsInternalAddress(IPAddress address)
+    {
+        if (address.IsIPv4MappedToIPv6) address = address.MapToIPv4();
+
+        if (IPAddress.IsLoopback(address)) return true;
+        if (address.Equals(IPAddress.Any) || address.Equals(IPAddress.IPv6Any)) return true;
+
+        if (address.AddressFamily == AddressFamily.InterNetwork)
+        {
+            var bytes = address.GetAddressBytes();
+            if (bytes[0] == 10) return true; // 10.0.0.0/8
+            if (bytes[0] == 172 && bytes[1] >= 16 && bytes[1] <= 31) return true; // 172.16.0.0/12
+            if (bytes[0] == 192 && bytes[1] == 168) return true; // 192.168.0.0/16
+            if (bytes[0] == 169 && bytes[1] == 254) return true; // 169.254.0.0/16 (incl. cloud metadata)
+            if (bytes[0] == 127) return true; // 127.0.0.0/8
+            return false;
+        }
+
+        if (address.AddressFamily == AddressFamily.InterNetworkV6)
+        {
+            if (address.IsIPv6LinkLocal || address.IsIPv6SiteLocal) return true;
+            var bytes = address.GetAddressBytes();
+            if ((bytes[0] & 0xFE) == 0xFC) return true; // fc00::/7 (unique local)
+            return false;
+        }
+
+        return true; // unknown address family: fail closed
+    }
+
+    private async Task TouchSyncStateAsync(string ownerUserId, string mode, string source, bool succeeded, string? error, CancellationToken cancellationToken)
+    {
+        var connection = await _db.ImapConnections.FirstOrDefaultAsync(x => x.OwnerUserId == ownerUserId, cancellationToken);
+        if (connection is null) return;
+
+        connection.LastSyncAttemptedAt = DateTimeOffset.UtcNow;
+        connection.LastSyncMode = mode;
+        connection.LastSyncSource = source;
+        connection.LastSyncStatus = succeeded ? "ok" : "error";
+        connection.LastSyncError = succeeded ? null : error;
+        if (succeeded)
+        {
+            connection.LastSyncedAt = DateTimeOffset.UtcNow;
+            connection.LastSyncSucceededAt = connection.LastSyncedAt;
+        }
+
+        await _db.SaveChangesAsync(cancellationToken);
+    }
+}

JobTrackerApi/Services/StartupInitializationExtensions.cs

@@ -386,6 +386,31 @@ public static class StartupInitializationExtensions
                     Exec(c, """CREATE UNIQUE INDEX IF NOT EXISTS "IX_MicrosoftGraphConnections_OwnerUserId_MailAddress" ON "MicrosoftGraphConnections" ("OwnerUserId", "MailAddress");""");
                 }
 
+                static void EnsureImapConnectionsTable(DbConnection c)
+                {
+                    Exec(c, """
+        CREATE TABLE IF NOT EXISTS "ImapConnections" (
+            "Id" INTEGER NOT NULL CONSTRAINT "PK_ImapConnections" PRIMARY KEY AUTOINCREMENT,
+            "OwnerUserId" TEXT NOT NULL,
+            "Host" TEXT NOT NULL,
+            "Port" INTEGER NOT NULL,
+            "UseSsl" INTEGER NOT NULL,
+            "Username" TEXT NOT NULL,
+            "EncryptedPassword" TEXT NOT NULL,
+            "ConnectedAt" TEXT NOT NULL,
+            "LastSyncedAt" TEXT NULL,
+            "LastSyncAttemptedAt" TEXT NULL,
+            "LastSyncSucceededAt" TEXT NULL,
+            "LastSyncMode" TEXT NULL,
+            "LastSyncSource" TEXT NULL,
+            "LastSyncStatus" TEXT NULL,
+            "LastSyncError" TEXT NULL
+        );
+        """);
+
+                    Exec(c, """CREATE UNIQUE INDEX IF NOT EXISTS "IX_ImapConnections_OwnerUserId" ON "ImapConnections" ("OwnerUserId");""");
+                }
+
                 static void EnsureCvTables(DbConnection c)
                 {
                     Exec(c, """
@@ -455,6 +480,7 @@ public static class StartupInitializationExtensions
 
                 EnsureGmailConnectionsTable(conn);
                 EnsureMicrosoftGraphConnectionsTable(conn);
+                EnsureImapConnectionsTable(conn);
                 EnsureCvTables(conn);
 
                 // Legacy DB signature: migration history exists (AddCorrespondence applied), but 20260310195000 not recorded,
@@ -634,6 +660,7 @@ public static class StartupInitializationExtensions
                     EnsureMySqlAutoIncrementPrimaryKey(conn, "JobEvents", "Id");
                     EnsureMySqlAutoIncrementPrimaryKey(conn, "GmailConnections", "Id");
                     EnsureMySqlAutoIncrementPrimaryKey(conn, "MicrosoftGraphConnections", "Id");
+                    EnsureMySqlAutoIncrementPrimaryKey(conn, "ImapConnections", "Id");
                     EnsureMySqlAutoIncrementPrimaryKey(conn, "CvUploadArtifacts", "Id");
                     EnsureMySqlAutoIncrementPrimaryKey(conn, "CvExtractionRuns", "Id");
                     EnsureMySqlAutoIncrementPrimaryKey(conn, "TailoredCvDrafts", "Id");
@@ -851,6 +878,30 @@ public static class StartupInitializationExtensions
                         cmd.ExecuteNonQuery();
                     }
 
+                    if (!HasMySqlTable(conn, "ImapConnections"))
+                    {
+                        using var cmd = conn.CreateCommand();
+                        cmd.CommandText = @"CREATE TABLE IF NOT EXISTS `ImapConnections` (
+        `Id` int NOT NULL AUTO_INCREMENT,
+        `OwnerUserId` varchar(255) NOT NULL,
+        `Host` varchar(255) NOT NULL,
+        `Port` int NOT NULL,
+        `UseSsl` tinyint(1) NOT NULL,
+        `Username` varchar(255) NOT NULL,
+        `EncryptedPassword` longtext NOT NULL,
+        `ConnectedAt` datetime(6) NOT NULL,
+        `LastSyncedAt` datetime(6) NULL,
+        `LastSyncAttemptedAt` datetime(6) NULL,
+        `LastSyncSucceededAt` datetime(6) NULL,
+        `LastSyncMode` varchar(255) NULL,
+        `LastSyncSource` varchar(255) NULL,
+        `LastSyncStatus` varchar(255) NULL,
+        `LastSyncError` longtext NULL,
+        PRIMARY KEY (`Id`)
+        );";
+                        cmd.ExecuteNonQuery();
+                    }
+
                     if (!HasMySqlTable(conn, "TailoredCvDrafts"))
                     {
                         using var cmd = conn.CreateCommand();
@@ -956,6 +1007,13 @@ public static class StartupInitializationExtensions
                         cmd.ExecuteNonQuery();
                     }
 
+                    if (!MySqlIndexExists(conn, "ImapConnections", "IX_ImapConnections_OwnerUserId"))
+                    {
+                        using var cmd = conn.CreateCommand();
+                        cmd.CommandText = "CREATE UNIQUE INDEX `IX_ImapConnections_OwnerUserId` ON `ImapConnections` (`OwnerUserId`);";
+                        cmd.ExecuteNonQuery();
+                    }
+
                     if (!MySqlIndexExists(conn, "TailoredCvDrafts", "IX_TailoredCvDrafts_OwnerUserId_JobApplicationId"))
                     {
                         using var cmd = conn.CreateCommand();