I sent an email, but it bounced and returned a Non-Delivery Report (NDR) with the following error:

554 delivery error: There has been an error delivering your message to Crossware Mail Signature.
ErrorCode=550 5.4.1 []: Recipient address rejected: Access denied



NOTE: This is a Microsoft Azure Active Directory query and is independent of Crossware Mail Signature.
For further support, please use this link:

There are two main causes of this error:
(A) The email recipient is a new user and has only been created in the last hour. This can result in the recipient address being rejected since the Azure Active Directory has not yet been fully updated by Microsoft.

If this is the case in your situation, please wait an hour and try again.

(B) The email recipient has been deleted as a user in the Azure Active Directory, but the deletion process has not removed the user from a Group within Windows Azure Active Directory.

If this is the case, you need to complete the deletion process manually through your Microsoft 365 environment by following these steps:
1. Log in to Microsoft 365, and access the Exchange Admin Center.

2. Go to Users > Deleted Users

3. Find the user's name in the list and click on them to discover what groups they are in.

4. Remove the user from all groups.

5. Alternatively, you can go to Groups, click on the group that you were sending the email to, and manually remove the user from this group.

If these solutions do not solve the issue, please contact Microsoft Support at
Related Products: CMS M365