Troubleshooting outbound mail after enabling the smarthost

You've enabled the smarthost but mail still isn't arriving as expected. Work through these in order.

1. Is the message reaching the relay at all? Check the dashboard's outbound log. If your message isn't listed, your mail server isn't actually routing through smtp.mxguard.uk — recheck the relayhost/smarthost setting and reload it.
2. Authentication failing? In 587/SASL mode, a wrong username or password gives an auth error in your server's logs. Reconfirm the generated credentials. In IP-allowlist mode, confirm you're connecting from the exact static IP you registered.
3. SPF still failing at the receiver? Make sure you added include:_spf.mxguard.uk to your (single) SPF record and that it published.
4. Hitting the rate limit? There's a soft limit of 2,000 messages/day per account; a sudden large send can trip it. If you legitimately need more, contact us rather than working around it — we'll talk about it instead of surprise-billing.
5. Attachment stripped or blocked? ClamAV scans outbound attachments; a message carrying detected malware is stopped. Check the affected machine for compromise.

Still stuck? The outbound log tells you whether each message was accepted, which quickly isolates whether the problem is on your side or at the destination.