When Theatre Manager sends an email it waits for a response from the outgoing mail server. If the mail server does not send back a reply within the timeout the email in Theatre Manager will be marked with a timeout error. The timeout is located in the
Web Server button of
Company Preferences in Theatre Manager. The most common cause for the mail server not sending a response back to Theatre Manager is a scan of the email before sending the email. Often this is caused by a Virus Scan of the email before it's sent out. This can happen at either the local machine level (applications such as Kaspersky) or be a part of the outing server software. Turning off the Virus Scan software for all outgoing email will resolve this issue.