Vista - Windows Mail Contact Group too large?

Hi
I am new to this.
I placed 143 contacts in a "group" (I have other groups with fewer contacts in them)
When I tried to send an email to this large group, an error message popped up telling me there were too many addresses in that group. My mail was then defaulted to the Outbox and sits there until I resolve this issue.

I don't want to break up that Group into four or five sections unless that is the only solution. I'd rather there was a solution that would allow me to use all 143 contacts in the single group.

Any suggestions?

Thanks

Noranna