Reads source code of new release, takes only what he likes. Instigates lawsuit against the vendor for having shipped a product with bugs in it in the first place. Well, it's upgrade time. Should take a few hours. Rewrites sendmail.cf from scratch.
Hacks kernel to implement file locking.
Rewrites sendmail in assembly. Hacks kernel to . . . Puts mail use policy in motd. Locks accounts that go over mail use quota. Keeps quota low enough that people go back to interoffice mail, thus solving problem.