Virtual domain
users need to use the following format for thier user name when
popping in:
user%virtual_domain_name
Eudora might require the following syntax:
user%virtual_domain_name@pophost
Microsoft clients may take the following syntax:
user@virtual_domain
If you don't include the %virtual_domain_name, vpopmail will
assume it is either a /etc/passwd user or a vpop user in ~vpopmail/users
or configured with "default domain".