If you think you may not have the most recent contact information for a person in your Overture contacts list, you can very easily ask them to update their own personal information for you.
Head over to the contact record you need updated and in the sidebar you can see the option to Send contact update request.
Depending on how you have your messages set up, this may be sent by Overture automatically or you may need to head over to your Outbox and send the email from there. See this article for more information on setting up your messages.
Once the message is sent all you need to do is wait. The contact in question will receive an email stating that you require updated contact information with a link to a form for them to fill in the relevant information. This screen will have your company logo at the top so the contact knows that the request is from you.
When the contact has completed and submitted the form you will receive a confirmation email letting you know and the information in Overture will update.