At 07:06 09/11/2003 Thursday, Xabier Altube wrote:
 >Hi all,
 >
 >I have a problem with a potential subscriber to one of our lists...
 >
 >He's  trying to subscribe with the address  John.O'Neill@.... and the
 >Listserv gives him an error saying that he has entered an invalid e-mail
 >address.

try a listserv cmd:

ADD listname John.O'Neill@host John O'Neill

I had NO problems with that syntax on a test list.

It may be that his MUA is not filling in the comment NAME field on the
RFC822 FROM: and he is not yet in the SIGNUP file.