Use this SR to request for the user's work email address if you notice they provided their personal email address. 

Thank you for contacting DOC MBDA CLC End-User Support!

For security reasons, we are only allowed to send login credentials or information to DOC MBDA Email Addresses. For us to assist you further, do you have access to your MBDA Email Address? If so, can you provide it to us, please? We look forward to your response.

Thank you in advance!