[exim] Unable to send mails to id's with apostrophe

Hi,

I am having exim4-daemon-heavy 4.50-8sarge2 on debian etch. When I send
mails to id's with apostrophe like the one below:

Frank.O'Donnell@???

I am getting "Remote host said: 550 restricted characters in address"
message. Can somebody please help me with this issue so that I can send
mails to such ids also?

Regards,
Biju Abraham N.