External mail clients (Postbox 3.0.9) can not send email 550 5.7.1 Client does not have permissions to send as this sender

Posted on 2014-02-20
Last Modified: 2014-02-28
Hi There,

Exchange 2010 environment.

External users can't not send email using Postbox (mac client)

Internal users are not affected just external users.
This was working perfectly fine in the past.

The error is: 550 5.7.1 Client does not have permissions to send as this sender

The same external users can send emails using Smartphone (Iphones) but not via email client.

Thanks, Rod
Question by:Rodrigo Carrilho
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LVL 14

Expert Comment

by:Andy M
ID: 39873222

What connection method is the Postbox software using to connect to the Exchange server? POP/SMTP, IMAP, EWS, OWA?

iPhones and Email clients connect in different ways to the exchange server. The phones use Activesync where as the email clients use one of the above connection methods. The fact that the phone works indicates the account is working with regars to sending/recieving email so the issue will be with the connection methdo used by the Mac client.
LVL 37

Expert Comment

by:Jamie McKillop
ID: 39873543

Make sure the client is set to authenticate before sending.


Accepted Solution

Rodrigo Carrilho earned 0 total points
ID: 39881233
thank you for the comments.

I managed to solve the problem by giving full permission the mailbox user itself.

Author Closing Comment

by:Rodrigo Carrilho
ID: 39894355
I managed to solve the problem by giving full permission the mailbox user itself.

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