Short answer
A bounce is an automatic reply saying a message could not be delivered, and the code in it says why. A 5xx code is permanent — wrong address, or you were rejected — and a 4xx is temporary, so the sending server will keep trying.
This is a general web-hosting explanation, not specific to Traxio.
The useful part is usually one line buried in the technical detail, naming the receiving server’s reason: mailbox full, no such user, or blocked for reputation. Read that line before changing anything.
Learn more
- Understanding email bounce messagesRead an email bounce (non-delivery report): the common 4xx and 5xx codes, what ‘mailbox full’, ‘relay denied’ and ‘rejected by policy’ mean, and what to do.
- Why are my emails going to spam?The real reasons email lands in junk folders — authentication, content, reputation and recipient behaviour — and a checklist to fix each one.
- Email blacklists (blocklists): how to check and what to doWhat email blocklists are, how to check your domain and sending IP, why a shared server can be listed, and how delisting works.
Step-by-step
- Diagnose email delivery problemsAdvanced · 40 min · 9 steps