Advanced SMTP options

Enable alternate catch-all header
When mail is sent to an invalid recipient and they are specified as a BCC on the message, it is difficult for the mail administrator to know who should have received the message. The Catch-All header allows you to specify the name of the message header field that is used to record any recipients that were delivered to the Catch-All account. By default, MailEnable records this information into the Received By: message header; hence this setting is supplied to provide more control over how the information is recorded within the message. Only one copy of a message with multiple recipients is delivered to the catchall mailbox.

Add required headers for authenticated senders if needed
Some email clients or applications will not add a Message-ID or Date header line to their emails. Some mail servers require these items and will reject the email if they do not exist. By enabling this option, MailEnable will add the required lines (if they do not exist) to all users who are authenticated to relay through MailEnable.

Allowed SMTP Commands
The list of SMTP commands that can be disabled are shown here. For example, it is possible to disable the EXPN, which displays all the emails of users in a group.