cannot bounce incoming spam mail

[o0CAPPI0o]

for about a week to two weeks i have suddenly been recieving spamm mail on my hostgator mail before i was able to bounce this mail (with mailwasher) fooling spammers into believing the email accounts did not exsist but for some reason i get a 550 error now saying the smpt server can not or will not send the message 550 admin prohibition but as far as i know the only alterations to stop incoming-outgoing mail was spam control but that should only affect incoming mail should'nt it.
can anyone help me out?