X-Sylpheed: A Complete Beginner’s Guide

2. Can’t connect to mail server (IMAP/POP/SMTP)

• Verify server address, port, and encryption (SSL/TLS/STARTTLS). Common ports: IMAP 993 (SSL), 143 (STARTTLS); POP3 ⁄₁₁₀; SMTP ⁄₅₈₇.
• Check username/password by logging into webmail or another client.
• Ensure network connectivity and DNS resolution: ping mail.example.com and telnet mail.example.com 993.
• If using two-factor or app passwords, confirm you use an app-specific password.
• Check firewall (local or router) and ISP blocking (some ISPs block port 25).

3. Authentication failures

• Re-enter credentials in account settings; watch for extra spaces.
• Confirm authentication method (plain, login, CRAM-MD5) matches server requirements.
• Check for required OAuth flows — if server mandates OAuth2, X-Sylpheed may not support it; use an app password or a client that supports OAuth2.

4. Mail sync issues (missing or partial folders/messages)

• Confirm subscription to IMAP folders in account settings.
• Force a full resync: remove and re-add the account or clear local cache (backup maildir first), then re-download.
• Check server-side filters or retention rules that may have moved/deleted messages.
• Verify folder namespace/prefix settings (e.g., “INBOX.”) if folders appear as top-level or under a different path.

5. Sending fails or messages stuck in Outbox

• Confirm SMTP server, port, and authentication are correct.
• Try sending a small plain-text message to test.
• Check Outbox logs or terminal output when sending.
• If using SSL/TLS, ensure certificate verification isn’t failing — try toggling certificate checks briefly for diagnosis (re-enable afterward).

6. Attachment problems

• Ensure attachments aren’t blocked by size limits on server; try sending via webmail to test.
• Check mail encoding settings (base64/quoted-printable) in Compose options.
• For corrupt downloads, try saving the attachment then opening with another program.

7. Search or indexing not working

• Rebuild the local index/search database if available (check for a command or delete index files in profile).
• Verify search settings (scope: headers, body, date range).

8. UI glitches or theme/rendering problems

• Try switching to a default or different GTK theme; some themes can break layout.
• Start with a fresh config (move config dir) to rule out corrupted UI settings.

9. Slow performance

• Compact/mailbox maintenance: remove large folders, archive old mail, or compact mbox/maildir files.
• Disable or limit filters/rules that run on every message.
• Check for network latency with IMAP servers; consider using offline mode for large mailboxes.

10. Corrupted mailboxes or missing messages

• Backup mail files (maildir/mbox) immediately.
• Use recovery tools like mboxrecover or formail (procmail) for mbox; for Maildir, inspect cur/new/tmp for lost files.
• Restore from server if using IMAP.

Logs, diagnostics, and next steps