VMTA stands for Virtual Mail Transport Agent. In a nutshell, a mail transport agent is (or mail server) is a software tool that forwards incoming email from senders for further delivery. VMTAs are email servers that assign different IP addresses to particular types of emails, e.g. transactional or promotional. Consistent sending patterns and cadence will help make sure your messages are going to their inbox rather than Spam or Junk folders.

You can apply a VMTA for a query or database used as the contact source for your program. The hierarchy between VMTAs is:

• If a parent database or a query has no other VMTA assigned, the organization's VMTA is used as default.
• If the query has a VMTA specified and that query is the contact source for the program, all emails sent from the program will use this VMTA.
• If a query is the contact source of the program and its parent database has a VMTA specified, the program mailings are sent from the parent database's VMTA.

If the VMTA assignment changes on an existing program, the program will automatically update the sends to use the new VMTA after midnight, for the next day's sends.

For more information about VMTA setup, see VMTA servers.