Error when sending email replies: 'Client does not have permissions to send as this sender'

When trying to send email replies, you may encounter the following error message:

550 5.7.1 Client does not have permissions to send as this sender.

In this topic, we'll explain the root cause of this error and show you how to quickly fix it.

Unlike a regular mailbox where you use your own username and password to authenticate to the account, outbound emails from GFI HelpDesk either:


For more details on the types of email addresses used by GFI HelpDesk, see For more information refer to Changing outgoing email addresses for automated emails.

By default, the email queue address is used as the From address of the sender. And since the email queue is using its own credentials, the mail server authenticates those details without a problem.

The error occurs when you try to select a different sender. For example, it commonly occurs when a staff user selects their own email address in the 'From' dropdown while updating a ticket. This results in an error because the outbound mailbox does not permit users to send on its behalf. It is commonly associated with Exchange/Office365 accounts which tend to restrict "send as" access by default.

For instance, when a staff user, Joe, replies to a support email, by default it is sent using the 'From' address of the email queue, which, in this case, is support@[yourcompany].com. However, if Joe were to select his own email address, joe@[yourcompany].com, in the 'From' dropdown, it creates a conflict and subsequently lead to the error since you are authenticating using the support@[yourcompany].com credentials but using joe@[yourcompany].com to send the email.


To resolve the error, you need to configure Send as permissions on your mail server so that staff email accounts can send email using your outbound mailbox account.

The instructions for doing this for some of the more common email servers/providers are listed below: