Mail provider switched, some senders keep mailing the old MX
After an MX switch, some senders hold cache on the old value and local relays can be stuck. End-delivery depends on whether the old MX still listens. Do not turn it off too fast.
Try this first
- 1Keep the old MX/server live for at least 7 days after cutover, with forwarding to the new MX so slow senders do not bounce.
- 2Lower MX TTL to 300 before the switch, so most resolvers pick up the new MX within an hour.
- 3Use Microsoft Message Trace or Google Workspace logs to check whether mail still arrives via the old route, and who the senders are.
- 4Only retire the old MX after 14 days of zero new mail through that side.
- 5For specific partners with your old server hardcoded (classic for EDI or billing tools), call them and have them update.
When to bring us in
If you still have mail in old infrastructure you cannot turn off and no view of who sends what, we can plan the decommissioning with monitoring.
See also
- Domain expires tomorrow and nobody saw the emailAn expired domain doesn't transfer instantly. There's a redemption window, but you pay extra.
- Unsure whether to enable auto-renewDisabling auto-renew only makes sense for domains you'll truly drop. For anything live, just keep it on.
- New registrar asks for auth code, can't find itEPP code or transfer code is the password to move a domain from registrar A to B.
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