On Mon, 05 Apr 2010 23:51:16 PDT, Stefano Sordini said:

> days/week) to no-less than 5.000 recipients. My manager informed me that
> we have to keep an upper limit of 30 seconds; i.e. all e-mails should
> have been sent successfully within 30 seconds.

Your manager has obviously never run an Internet-facing mail server.

5,000 recipients?  Failing to get 98% delivered in 30 seconds usually means
you've misconfigured your mail server, assuming anything close to modern
hardware.  We've often had 80,000 recipient postings, and gotten 98%
of that out the door in under a minute (and not on big iron either -
a older Dell 2850 with 2 3.6GHz Xeon CPUs and 2G of RAM).

But you can't get 100%.  Simply won't happen, because at any given time,
one or two percent of the far end sites are down.  If you have Hotmail
recipients, and Hotmail is having another one of its perennial 'reply-421'
tiffs where it sulks and refuses to accept mail, you have no choice but
to queue it up until it's willing to accept it several hours later. (And it's
not just Hotmail - I've seen *every* free-mail site do this at one time
or another).

And you *will* have recipients that are at small sites that have one IT
guy, and the disk on their server has just crashed at at 5:45PM on a Friday.
You *know* that won't even get looked at till Monday morning, and if the
one guy doesn't have clue, it might be Wednesday before they get the mail
server back up and running.

There's a *reason* why most mail servers come configured with "keep retrying
for 3 days" or "5 days" before giving up and bouncing the mail.

Tell your boss that you'll be more than happy to guarantee 98% in 30 seconds,
but won't guarantee 100% unless your boss can guarantee the behavior of the sites
you're trying to send to.