PHP, sendmail, and mail() - VERY SLOW - please help

I'm working with a LAMP platform - PHP 5.1.4, MySQL 5.0.21, RedHat
Enterprise 4... Running Sendmail 8.x.

I'm using the PHP mail() function to send some confirmation emails out
when a user submits a form. My understanding is that this is basically
a wrapper for sendmail (specifically, sendmail -t -i).

In my development environment, this works great. Everything is fast
and wonderful.

In my production environment, it takes 10-15 seconds or more before the
mail() function completes. If I comment out that function, the page is
nice and quick again.

Does anyone have any ideas of what sort of configuration issue this
might be (I'm assuming this is a config issue). My sendmail config
(/etc/sysconfig/sendmail) is pretty simple right now, it's just
specifying DAEMON=yes and QUEUE=1m.

Any advice would be much appreciated. Thanks in advance.

Evan

What is in the sendmail log? Different dns? More info?

todh