Error message 17099 with Entourage

[kparks]

This is the error message I receive when I try to send a group email using
Comcast as my email provider and Entourage. When I use Mac's "mail" program, I can send group emails without a problem. When I say "group" I mean recipients less than 12 people (not 40 or 50 people which I know can be confused often with spam).
I have contacted Comcast and they say that they can't help me - it is a problem with my Mac configuration...
So....what do I do to correct this? I'd like to still use Entourage as my email software but will switch to the "Mail" software if this continues as it is most frustrating.
thanks for your help!


5.5.0 <> missing or malformed local part

Mail could not be sent
Account name "Kathy"
Error: -17099

[ElDiabloConCaca]

It looks like it's failing on "Kathy" -- is Kathy's email address correctly set up in the Entourage database?

From Googling the error, it seems like that error means that one or more of the email addresses you're trying to send to either doesn't exist or is malformed/missing/incorrect.

[CatMom]

The addresses work fine when I send to only one so I know my email is sending and I am sending to a valid email address. But when I try to send to a group of only 5 recipients, I get the error. I am running out of ideas.

Thanks,
A different Cathy