Tertiary-mx: Difference between revisions

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<indicator name="Faults">[[File:Menu-email.svg|link=:Category:Email|30px|Back up to the Email Category]]</indicator>

<indicator name="Faults">[[File:Menu-emailadd.svg|link=:Category:Email Features|30px|Back up to the Email Features Category]]</indicator>

tertiary-mx.co.uk is our backup email server. It will accept email for a domain we handle email for and will queue messages and will attempt to deliver to the higher priority MX record.

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*Invalid HELO

*Recipient domain is not one we handle email for

*Message size is over ~~1Gb~~.

*Message size is over 1GB.

*The server will 'greylist' hosts. It will always defer (cause a temporary delivery failure) messages/connections under the following circumstances:

*Sending host in a DNS ~~blacklist~~

*Sending host in a DNS blocklist

*Header syntax errors

*Recipient rejected by the primary MX (It does a call back to the primary MX if it is available)

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===etrn===

To force ~~tertiatry~~-mx to attempt to relay stored messages, telnet in on port 25 and issue an etrn command in the form of

To force tertiary-mx to attempt to relay stored messages, telnet in on port 25 and issue an etrn command in the form of

etrn #your-domain.co.uk

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quit

221 relentless.aa.net.uk closing connection

Note that tertiary-mx has various measures in place to discourage spam. You need to wait until after the "220 You are 2001:8b0:0::1" line is printed before you can issue the etrn, which may take a few seconds. Mismatching forward/reverse DNS etc. may upset it when you try to telnet in. If possible telnet in from your mail server itself, as that is more likely to look trustworthy.

==Setup==