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> |
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<indicator name="Faults">[[File:Menu-emailadd.svg|link=:Category:Email Features|30px|Back up to the Email Features Category]]</indicator> |
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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. |
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 |
*Invalid HELO |
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*Recipient domain is not one we handle email for |
*Recipient domain is not one we handle email for |
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*Message size is over |
*Message size is over 1GB. |
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*The server will 'greylist' hosts. It will always defer (cause a temporary delivery failure) messages/connections under the following circumstances: |
*The server will 'greylist' hosts. It will always defer (cause a temporary delivery failure) messages/connections under the following circumstances: |
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*Sending host in a DNS |
*Sending host in a DNS blocklist |
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*Header syntax errors |
*Header syntax errors |
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*Recipient rejected by the primary MX (It does a call back to the primary MX if it is available) |
*Recipient rejected by the primary MX (It does a call back to the primary MX if it is available) |
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==Queuing== |
==Queuing== |
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Messages will be attempted to be sent on to a higher priority (i.e. lower MX record) email server starting at every 15 minutes, and increasing over time to every 3 hours. It will carry on trying for 31 days before bouncing the message back to the sender. |
Messages will be attempted to be sent on to a higher priority (i.e. lower MX record) email server starting at every 15 minutes, and increasing over time to every 3 hours. It will carry on trying for 31 days before bouncing the message back to the sender. |
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===etrn=== |
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To force tertiary-mx to attempt to relay stored messages, telnet in on port 25 and issue an etrn command in the form of |
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etrn #your-domain.co.uk |
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For example: |
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$ telnet tertiary-mx.co.uk 25 |
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Trying 2001:8b0:0:30::51bb:1e1d... |
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Connected to tertiary-mx.co.uk. |
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Escape character is '^]'. |
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220-relentless.aa.net.uk ESMTP Thu, 08 Sep 2016 09:30:29 +0100 |
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220-Mail accepted subject to terms on http://www.andrews-and-arnold.ltd.uk/inboundemailterms.html |
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220 You are 2001:8b0:0::1 |
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etrn #example.com |
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250 OK |
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quit |
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221 relentless.aa.net.uk closing connection |
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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. |
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==Setup== |
==Setup== |
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If you would like to use tertiary-mx.co.uk as a backup mail server for your domain please contact sales who will add the domain. |
If you would like to use tertiary-mx.co.uk as a backup mail server for your domain please contact sales who will add the domain. |
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If you manage your own DNS server, then you'll want to add an entry similar to: |
If you manage your own DNS server, once added at our end, then you'll want to add an entry similar to: |
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example.com MX 50 tertiary-mx.co.uk. |
example.com MX 50 tertiary-mx.co.uk. |
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