Feb 23, 2020 
Support Center » Knowledgebase » Office365 Permanent Delivery Failure Errors
 Office365 Permanent Delivery Failure Errors
Solution The following message had PERMANENT fatal delivery errors!
<<< 550 5.7.1 Client does not have permissions to send as this sender

This is an issue with Office 365 in that by default they only allow outbound messages to be From: the email address that is logging in to send the message.

So if you have your Message Destination in MailFlow configured to authenticate to Office 365 as the user sales@domain.com but the outbound message is from a different email address then you will receive the error 550 5.7.1 Client does not have permissions to send as this sender.

To resolve this issue you have to add your MailFlow From: email addresses to the Office 365 account that is configured in the Message Destination.

You can follow the steps at this link to add them: http://support.microsoft.com/kb/2600912

Go to the section titled "How to support multiple email addresses" and follow the steps in "Method 2: Add proxy addresses".

So if you have a TicketBox in MailFlow with an email address of info@domain.com you need to add the info@domain.com email address as a Proxy Address to the sales@domain.com Office 365 account. This will allow outbound email From: info@domain.com to be sent via the sales@domain.com Office 365 account.


Article Details
Article ID: 770
Created On: Jul 11, 2013 01:01 PM

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