Sendmail & Queuing

["Jason McMullen" <jmcmullen@ins-business.com>]

Good Day All,

I'm running into an odd issue.  We have 2 servers that act as
"front-end" MX hosts running Sendmail.  These servers then smarthost all
mail back to a main server.  This works well at keeping the main server
unloaded due to dictionary attacks and whatnot.  The problem we're
seeing is the MX hosts bogging down when trying to deliver mail to the
main host.  

Does anyone have any tried and true methods for getting Sendmail to be a
little "nicer" about its queuing strategy?  Or is the best option qmail
or another MTA?

TIA!

-Jason