All:
>
>I have sent a couple of messages in the past few days, and while I have
>received
>back a reply that it has been accepted, I have also been receiving the
>following
>a few hours later, any idea of what might be happening?
 
It means that:
 
>>To: [log in to unmask]
 
and whoever was in the To: field of the deleted other header do not have
working mailboxes at this time. The daemon is just trying to tell you who
didn't get it. I believe we will all get similar messages until these
addressees are removed from the list. Just ignore them.
 
!================================:^0
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