OT - How to stop an account from receiving mail without deleting the account?

[Jayson Smith]

Hi,

     I run a Linux server via VPS. The 'mail' account is getting tons and 
tons of spam, so I'd like to start bouncing messages to that account. But I 
presume bad things will happen if I outright delete the mail account, right? 
My MTA is Sendmail. Is there any way to tell the system not to accept mail 
for that account? I tried aliasing it to a nonexistent user, but the mail 
still gets accepted, then it bounces since the alias points to total junk, 
then more often than not the bounce bounces, so Postmaster gets the bounced 
bounce, generated from a message I never even wanted in the first place! So 
is there a way to tell it, as soon as it sees that the message is for mail, 
error out right there?
Thanks,
Jayson