Mail Delivery Failed: Restricted Characters

Here we will cover the situation when a recipient's email address uses special ASCII characters, and cPanel cannot send an email to the email address successfully.

This issue can be seen by receiving "Mail Could Not Be Delivered" error messages and with the recipient's email address including special characters such as !.  The diagnostic code on the bounce back may appear as 550 restricted characters in recipient address.

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Working around the Issue

1. You will need to contact the recipient using a different method if the recipient's email address uses one of the restricted characters
2. The following characters are restricted and cannot be used in the recipient's email address
   • !
   • #
   • ?
   • `