On 6/1/2010 9:01 AM, Kaleb Hosie wrote:
Hey All,
I have a user trying to send an email however it was bounced back. After
checking the maillog, I found that it was timing out when sending "RCPT TO".
I telnet'ed into the recipients server and started sending the series of
commands to send mail and it seemed very quick up until I sent RCPT TO; it
proceeded to hang there for 50 seconds before responding with a 250 SMTP
code. I was able to get the email to send by increasing the timeout period
to 60 seconds for "RCPT TO".
My question is what is the purpose in the delaying that SMTP code? Would it
be advantageous to implement that into my Postfix configuration?
There is no benefit to adding a delay after RCPT TO. It would
not be helpful -- and likely harmful -- to add a delay at that
point to postfix.
My guess is that the receiving system is doing some sort of
anti-spam analysis during this delay, such as real-time
address verification probes or excessive RBL lookups or maybe
they are checking some dead RBLs that time out. If such tests
take 50 seconds something's broken.
But ultimately, speculation is pointless. You'll need to
check with the postmaster of the remote system to find out why
their RCPT TO has excessive delays.
-- Noel Jones
