|Message:||SMTP rejected a (%4) mail from ‘%1’ with ‘%2’ connector and the user authenticated as ‘%3’. The Active Directory lookup for the sender address returned validation errors. %5|
This Error event indicates a problem validating the e-mail address of a sender that was using “Send as” permission to send a message. The Active Directory directory service lookup for the sender’s address returned the specified validation errors.
The “Send as” permission allows recipients to send e-mail messages as if the message originated from a different recipient. Specifically, recipients who are granted the “Send as” permission to any mail-enabled object can enter the other recipient’s name in the From field for the messages that they send.
For example, assume that Michelle has been granted “Send as” permissions for the mailbox of her manager, Laura. Michelle sends a message to Julia with Laura’s name in the From field. When Julia receives the message, it appears as if it was sent by Laura.
For more information, see: How to Grant Send As Permissions for a Mailbox.
To resolve this error, do one or more of the following:
If you are not already doing so, consider running the tools that Microsoft Exchange offers to help administrators analyze and troubleshoot their Exchange environment. These tools can help you make sure that your configuration is in line with Microsoft best practices. They can also help you identify and resolve performance issues, improve mail flow, and better manage disaster recovery scenarios. Go to the Toolbox node of the Exchange Management Console to run these tools now. For more information about these tools, see Toolbox in the Exchange Server 2007 Help.