error from PC-Yarn cc's

From: Larry Levine (levinel@humboldt1.com)
Date: Wed, 03 Mar 1999 20:07:56 -0800

Greetings:

For some reason my ISP's mail server is not accepting multiple cc's
from PC-Yarn, though there is no problem via Eudora. I believe the
cc's are properly formatted, with a comma between each (plus a
space), and subsequent lines indented. For what it's worth the
uploads are done with the UKA_PPP SMTP client.

The ISP's "Mail Delivery Subsystem" (Sendmail-Pro?) invariably
autoresponds with an error message that seems to show the cc line
split irregularly -- not at a comma. Two examples:

"Host unknown (Name server: axe.humboldt1.edu,levinel: host not
found"
"... (Name server: telis.org,: host not found"

Any insights?
cheers, Larry