[ExI] Fwd: Delivery Status Notification (Failure)

[John Klos]

> I get the same error and I don't have gmail. That leads me to believe that 
> the error is server-side and not client-side.

When we have limited information, we sometimes come to conclusions that 
make sense but aren't necessarily correct. Luckily, we have logs ;)

For your mail server (mail-gate.swisscows.email), it seems that the 
reverse DNS PTR for that server should point to a primary name, but it 
does not (RFC 1034, section 3.6.2, for anyone who is curious). But that's 
not directly why email was rejected, though - it was rejected because the 
extra lookup due to that CNAME took too long, which is why it happens only 
sometimes.

You can write to your email provider and let them know, and perhaps 
they'll fix it (feel free to include that paragraph and/or cc me - I'm 
happy to provide logs and more informtion). Isn't it better to fix the 
problem than the symptom? :)

For MB, I only see three failed attempts back in August and October. If 
this is happening more often than that, then I'd need more specific 
information to find any rejections in the mail logs (the logs are 
typically thousands of lines a day). Feel free to email me directly, if 
this is the case.

I do see that describing this as "Intrusion" can be a bit misleading. I 
put that in there for all of the connecting machines that attempt to log 
in to try to send email through the server, and it matches clients that 
don't identify themselves AND servers that have names that don't resolve 
(even if it's just temporary).

To make this less of a pain, I'm making the error transient so your email 
server(s) will retry before they fail. You might get a warning, but you 
won't have to do anything yourself.

I'm also changing the message to "Given name from (client_addr) does 
not make sense."

I'm sending this to the whole list to encourage anyone who has issues to 
contact me directly. Whatever happens, we'll figure it out!

Thanks,
John