Mail groups no longer sending

[RebelGood]

G5, 10.4.4. All of a sudden I can't send mail to a group from my address book. If I expand the group so that all the addressees appear it will send. If I create a group with only one member it will NOT send using the name of the group. This worked before the 10.4.4 update. What gives?

 

[RebelGood]

And another thing . . . it works normally when I take my laptop to another ISP — not Earthlink — and sent through their mail server.

 

[Mitthrawnuruodo]

If I expand the group so that all the addressees appear it will send.

What do you mean by if you expand the group...? Haven't you checked the "When sending to a group, show all member addresses" in Mail preferences -> Composing -> Addresses? That's always worked for me, and still does...