Nope, I surely did not change any list with the exception of hiding the address I am trying to sendas. But even before I hid it from the GAL I was experiencing the same issue.
My set up is so basic. . . 45 email address, 1 is a postmaster account (is also a catch-all).
While I am in my Outlook 2010, I want to be able to forward mail that comes to the postmaster as a result of the "catch-all" to the correct party.
It's annoying to have to remove and re-type every time, and why should I have to? I know you know what I mean.
I wanted to set/verify my setting so I ran these:
Give user full mailbox rights:
Add-MailboxPermission -Identity $mailbox -User $user -AccessRights 'FullAccess'
Give user send-as rights to mailbox:
Add-ADPermission -Identity $mailbox.DisplayName -User $user -ExtendedRights 'Send-as'
Everything I have done so far says it should be working as EMS tells me "The appropriate access control entry is already present on the object"
I've seen other blogs about this same issue with no resolve. However, I see that we are the only two that figured out removing the address and re-typing is a valid work around - a pain in the a*s, but still a work around.
I'll keep searching. . . and if/when I find something, I will be sure to come back here to let you know.