[Citadel Support] Re: Two smtp relays: citadel should use second relay when first one fails.

[IGnatius T Foobar]

 >      Oops I cannot remember and in this moment I cannot reproduce it. 
But I   
 >am 90% it was 5xx permanent error (e.g. using isp1 relay service with 
isp2   
 >adsl line is not allowed).   
   
 5XX permanent errors aren't supposed to be retried.  5XX means "stop."  
If it were a 4XX transient error, then we ought to move on to another 
relay (we don't, but a lot of mailers share this problem).