# Mail Transfer Agent (MTA)

*Internet standard*. A system that transfers email messages from one computer to another using a client-server application architecture. These typical MTA is an [SMTP server][smtp-server].

An Mail Transfer Agent (MTA) implements both the client, or sender, and server, or recipient, portions of the [Simple Mail Transfer Protocol (SMTP)][smtp].

To learn more, see the Twilio [Email Infrastructure Guide][].

[Email Infrastructure Guide]: https://www.twilio.com/en-us/resource-center/the-email-infrastructure-guide-build-it-or-buy-it

[smtp]: /docs/sendgrid/glossary/smtp

[smtp-server]: /docs/sendgrid/glossary/smtp-server