[SATLUG] Slow Email Sending

[Richard Maynard]

On 11/3/07, Samuel Leon <leon36 at gmail.com> wrote:
> Ok I got a funny question.  Why do some emails get sent really slow?  I

Well, if they go the route of the ones in the GMail Mail Delivery
video, then they might be pretty slow.... Otherwise, there are a slew
of reasons why some mail comes through slow.

> right now made a new account and it was working fine locally.  I tested
> it remotely by sending an email to it from myway.com, gmail, and juno.
> I waited and waited.  10 minutes passed and still nothing.  I finally

If you view the complete headers of the emails once you do get them,
you can follow the path they took from origin to destination, and
usually the timestamps associated with the different servers will give
you an idea of WHERE your message is getting slowed down at. The mail
headers are likely going to be more useful than your local logs, or
looking at your local traffic since it's only going to help with the
last step of mail delivery.

> tried sending it an email from a remote email server that a friend runs
> (it relays off of a grande communications server).  I checked the logs
> on his side and everything looks fine:
> to=<xxx at xxx.xxx>, relay=mail.grandecom.net[66.90.130.74]:25, delay=0.79,
> delays=0.17/0.02/0.16/0.43, dsn=2.0.0, status=sent (250 2.0.0
> lA47ktr03001 Message accepted for delivery)
> Yet here it is an hour later and I still have nothing.  Lucky some of

His logs show him handing off the mail to mail.grandecom.net, but you
lose visibility after that, once the message comes in, take a look at
the headers and see where the mail spent the most time.

> the other emails I sent from the other servers are starting to trickle
> in.  I don't think this problem is on my side.  I have never seen delays
> like this though.  Is this just typical of enterprise level servers?
> Some kind of queue where the messages wait in line for hours waiting to
> be scanned/sent?

Usually delays are not quite so long, but there are times when levels
of spam are just really high, or large email providers having
technical problems slowing inbound mail, that email gets slower. It's
rough for mail servers trying to do delivery to remote hosts that
aren't accepting connections.

> Also I see in the log clip above "delays=" and "delay=".  Is that some
> kind of local statistic or what?  I can't find anything on google.

That looks like the sort of delay logging that postfix sticks in the
header to help with diagnosing mail delivery issues. There may be
other MTA's that use it besides postfix, but I'm not aware of which
ones they are off hand. The delay is the total delay, and delays is
the delay split into the following feilds

time the message was alive before going to a delivery queue
time the message is in a queue
time to do: DNS Lookup, establish connection, and issue HELO and get
220 response
time to actually send message over the network.

-- 
Richard Maynard