In some cases you may have contacts or mailboxes(on Exhcange) that have custom SMTP addresses
associated with them. Users may be using these addresses(with some SMTP client) as source addresses
for sending e-mails to their peers.
When their peers receive the e-mail they will see the sender in standard SMTP format.
If you want them to see the sender as a standard user(no trailing SMTP address) you might
want to take advantage of ResolveP2 Functionality.
This is described in:
Keep in mind though that some see in enabling this functionality a security threat since
anyone can configure a specific address as the senders address and thus try to pose as
a legitimate user…My opinion is that if this is the only way of identifying a fraudulent e-mail
then you are introuble…