When using majordomo-type list servers, I've had occasional
problems with messages delivered to CompuServe and AOL -
where the email addresses on those domains were seen by
the other subscribers at that domain. It's never been a
serious problem - maybe 2-3 times for both CIS and AOL over
a few year time period.
I've never seen this happen with MSN before, but in the
past few days, I've had a few reports from different lists
delivered Thursday to Saturday that this has been happening
with MSN recipients. (i.e. they see the addresses of any
other MSN recipients because the addresses are expanded))
Meanwhile, I know it's not happening with all of our lists.
I know that this is not something unique -- before we
had our own list hosting service, I'd seen this happen
when our own lists were hosted with other companies.
Anyone have any ideas on what causes this to happen? I know
how the messages are delivered via majordomo-type software
(i.e. batches are delivered to each domain rather than an
individual message to each address), but the how and why
of the addresses being expanded has me baffled.