A proposal to remove sendmail and replace it with postfix has resulted in a variety of reactions. Matthew Dillon is surprisingly frustrated with sendmail, though Claude Assman, who is working on Sendmail X (the rewrite of Sendmail), says there are improvements.
Sascha Wildner pointed out that we get immediate, direct vendor support for Sendmail, such as the update today to 8.13.7 by Gregory Neil Shapiro, which is unlikely to happen with any other MTA.