I know I've asked a similar question before but I've got real problems with this.
We hold a bunch of domains (20 or so) and each of our users needs to accept and send mail for any domain (they're used for different business purposes). I can set people up with a long list of alternative addresses but I can't seem to send from them, only the default. If I try 'From' then I get an error abasout delegation. Surely if that address is mine then I should be able to use it. Setting them up as individual premium users and delegating authority is not an option as I'd need 400 or so licences to run a small office.
Is there any way at all I can sort this?
Also, we can't go back to using IMAP because IMAP has no mechanism for changing passwords which we need to force for ISO 27001 purposes.