The best services for SMTP mailings

A guide to choosing an SMTP server for email marketing

What Is an SMTP Server?

SMTP servers are complicated, and if you’re just dipping your toe into the how-email-gets-sent world, it’s easy to feel overwhelmed. To help you navigate your email sending, we’ve put together a list of the most common SMTP server questions we receive, so you’ll be an SMTP expert in no time. 

What is an SMTP server?

An SMTP (Simple Mail Transfer Protocol) server is an application that’s primary purpose is to send, receive, and/or relay outgoing mail between email senders and receivers. 

An SMTP server will have an address (or addresses) that can be set by the mail client or application that you are using, and is generally formatted as smtp.serveraddress.com. (For example, Gmail’s SMTP server address is smtp.gmail.com, and Twilio SendGrid’s is smtp.sendgrid.com. You can generally find your SMTP server address in the account or settings section of your mail client.)

When you send an email, the SMTP server processes your email, decides which server to send the message to, and relays the message to that server. The recipient’s inbox service provider, such as Gmail or AOL then downloads the message and places it in the recipient’s inbox.

You can find more details on SMTP servers on our docs page.

Is an SMTP server the same as a normal server?

Technically, yes. Like most servers, the SMTP server processes data to send to another server, but it has the very specific purpose of processing data related to the sending, receiving, and relaying of email. An SMTP server is also not necessarily on a machine. It is an application that is constantly running in anticipation of sending new mail.

Why are SMTP servers important?

Without an SMTP server, your email wouldn’t make it to its destination. Once you hit “send,” your email transforms into a string of code that is then sent to the SMTP server. The SMTP server is able to process that code and pass on the message. If the SMTP server wasn’t there to process the message, it would be lost in translation. 

Additionally, the SMTP server verifies that the outgoing email is from an active account, acting as the first safeguard in protecting your inbox from illegitimate email. It also will send the email back to the sender if it can’t be delivered. This informs the sender that they have the wrong email address or that their email is being blocked by the receiving server.