Apologies Carl
You are correct. When I view the mail source the Reply-To looks correct but my MUA (Evolution) is displaying it in the mangled form I mentioned and only on messages since the server move. When I look at the message source on the mail server itself there is a subtle difference between the messages before and after the move:
Before: Reply-To: "openacs.org mailer" <mailto:notification-1605297-2960@openacs...
After: Reply-To: openacs.org mailer <mailto:notification-1631369-2960@openacs...
Obviously Evolution doesn't like the lack of quotes.
- Steve