MX choosing

[Torsten Segner]

Am Fri, 22 Jul 2011 16:50:35 +0800
schrieb Feng He <shorttag at gmail.com>:

> Given the MX hosts for sympatico.ca domain:
> 
> $ dig sympatico.ca mx +short
> 5 mxmta.sympatico.ca.
> 
> $ dig mxmta.sympatico.ca +short
> 67.69.240.17
> 67.69.240.24
> 67.69.240.22
> 67.69.240.23
> 67.69.240.21
> 67.69.240.20
> 67.69.240.19
> 67.69.240.18
> 
> 
> when the peer MTA fail to talk to one of these hosts,will it try the
> next one? or it just give up?
> 
> Thanks.
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Since there's no fallback MX the MTA will try once and then store the mail for a later retry (depends on how your MTA is configured).
Since the TTL of mxmta.sympatico.ca is just 1800 seconds there might be a good chance that your MTA will try another server unless the next try is within 1800 seconds (where it will just reuse the already cached one) or your bad luck provides you with the not working IP address again.


Ciao
Torsten