Fastmail
Fastmail uses app passwords for every SMTP connection. Your regular Fastmail login password will not authenticate over SMTP — that’s true even if you don’t have 2-step verification on, because Fastmail requires per-app credentials for all IMAP / POP / SMTP / CardDAV / CalDAV access.
1. Generate an App Password
- Sign in at fastmail.com.
- Open Settings → Privacy & Security.
- Find the Connected apps & API tokens section.
- Click Manage app passwords and access → New app password.
- Give it a name —
Xenoceptworks. The label appears in the list later so you can revoke just this one. - Access: the default setting Mail, Contacts & Calendars is fine. (Or pick Mail alone if you’d rather scope it.)
- Click Generate password.
- Fastmail shows the generated password — a long random string. Copy it now. You can re-display it from the same screen later if needed.
2. Configure the Email Destination in Xenocept
Open the Xenocept Settings UI → Destinations → New Destination → Email. Fill in:
| Field | Value |
|---|---|
| SMTP Host | smtp.fastmail.com |
| SMTP Port | 465 (Fastmail’s recommended port — implicit TLS) |
| Security | SSL/TLS |
| Username | Your full Fastmail address (e.g. [email protected], or your custom domain if you use one) |
| Password | The app password from step 1 |
| From | Same as Username |
| To | Where you want sessions delivered |
Save the destination and submit a test session.
Port 587 also works. Fastmail accepts STARTTLS on port 587 if 465 is blocked for you, but 465 with implicit TLS is their stated preference.
Custom Domains
If you’ve added a custom domain to Fastmail, the Username for SMTP is still the Fastmail-managed primary address — but the From address can be any verified alias on your custom domain. Xenocept’s Email destination accepts independent From and Username values, so put your custom-domain address in From and your Fastmail login address in Username.
Revoking Access
- Return to Settings → Privacy & Security → Connected apps & API tokens → Manage app passwords and access.
- Find the
Xenoceptentry. - Click Revoke or the trash icon.
The app password becomes invalid immediately.
Common Issues
- “Authentication failed.” You used your Fastmail login password instead of the app password. Fastmail rejects the login password for SMTP — generate an app password.
- “Connection refused” on port 465. Some networks block port 465. Try port 587 with STARTTLS.
- Recipient policy. Fastmail enforces sending limits to protect against abuse. Heavy automated traffic from a new account may get throttled briefly. For typical Xenocept use (sessions on demand, not bulk mail), you’ll never hit the limit.