When a user receives a message where the From: field has the email address in both the display name part and the email address part, Outlook displays the message as "someuser@"

When these messages are replied to the To: field looks like "someuser@ <somedomain.com someuser@somedomain.com>

This happens with external messages sent to an exchange account. Comparing one message sent to both an exchange account and a different email address received on an Outlook client reveals that this only happens when sent to the exchange account. I have seen this on completely different domains using exchange. It's as though when the display name contains the @ symbol, exchange considers this a delimiter and whatever is left is put in the email address part. Has anyone else ever experienced this? 

Hi,

I never seen this problem before, and I will try my best to help you. Based on your description, I know the external email address contains the @ symbol in display name. But I couldnt understand the To: field "someuser@ <somedomain.com someuser@somedomain.com> in your post.

Can you please post a screenshot help me to understand this problem better?

Note: please hide sensitive information.

Thanks,

Best Regards.