421 Unexpected failure, please try later

[m***@bt.com]

Folks

Some of my users have been getting 421 errors when trying to send email
from their systems via my servers. None of this is logged by Exim on my
server. The customers logs are getting something like

SMTP command failed when talking to smtp.xxxxxx.net: <<< RCPT
TO:<***@xxxxx.co.uk> >>> 421 Unexpected failure, please try later



I'm not sure what the 421 means. I had though that it meant that there
were no available connections left but it appears to be set for other
reasons too (like AOL use it when rejecting mail because the sending IP
has been flagged for spamming).



What does it mean?

Can I log whenever my server sends this message to connecting hosts?

How do I measure what the current connections are for my server?



Thanks

Martin

[Steven Wayne]

Post by m***@bt.com
Some of my users have been getting 421 errors when trying to send email
from their systems via my servers. None of this is logged by Exim on my
server. The customers logs are getting something like
SMTP command failed when talking to smtp.xxxxxx.net: <<< RCPT

I would try and telnet to port 25 on your server to help you out, but
I suspect you've lied about the server name.

Post by m***@bt.com
I'm not sure what the 421 means. I had though that it meant that there
were no available connections left but it appears to be set for other
reasons too (like AOL use it when rejecting mail because the sending IP
has been flagged for spamming).
What does it mean?

Have you googled?

Post by m***@bt.com
Can I log whenever my server sends this message to connecting hosts?
How do I measure what the current connections are for my server?

Is there a /var/log/exim/reject.log you could look at?

Steven.

[Rafa]

Post by m***@bt.com
Folks
Some of my users have been getting 421 errors when trying to send email
from their systems via my servers. None of this is logged by Exim on my
server. The customers logs are getting something like

It's odd that there's nothing in your logs. Are the users behind some sort
of transparent smtp proxy? Some antivirus programs include this feature (so
they won't have to modify your mail client settings). If the client does a
"telnet smtp.xxx.net 25", does your server answers? While they do this, do
you see the connection on your server (netstat -na | grep ip.add.re.ss or
exiwhat | grep ip.add.re.ss)

Post by m***@bt.com
I'm not sure what the 421 means. I had though that it meant that there
were no available connections left but it appears to be set for other
reasons too (like AOL use it when rejecting mail because the sending IP
has been flagged for spamming).
What does it mean?

Temporary failure. Google for "smtp reply codes" for a more complete
answer/list

Can I log whenever my server sends this message to connecting hosts?



It should be logged by default in mainlog and rejectlog.

How do I measure what the current connections are for my server?


"exiwhat" gives a breakdown of what every exim process is doing. Count the
"handling incoming connections" or use "wc -l" or the like.

Hope this helps.