[fetchmail]fetchmail: SMTP error: 501 Bad address syntax

Hi all,

I admin a small network and in the past couple of days a few of our 
emails have been getting emails from addresses like this: 
wd77osuxj(_at_)%RND_LC_CHAR[5-14]@worshipworld.com
When fetchmail fetches the mail, it gets rejected by postfix
fetchmail: SMTP< 501 Bad address syntax
is there anyway to stop this happening as it will not recieve any mail 
for those few accounts now.
Thank you