Sendmail not receiving mail

["Dr. Orange" <alonsos1@gusun.georgetown.edu>]

I just noticed that after the upgrade from slink to potato, sendmail is no
longer receiving messages, or something to that extent - i can't send
emails to the server. Sending from the server works fine. 
I imagine this problem could be due to a number of issues, but I thought
i'd ask if anyone had the same problem when upgrading, or might know
off-hand what its cause is. 
If the mc or any other config file would be of help, please let me know
and i'll send it. (I didn't want to send an attach to the whole list) 

Thanks :))

-S-