Everyone wants a successful delivery of their email. What stands between desire and real success is the correct port of transmission. You might think that it is not much of your problem because the service provider worries about that.

Nevertheless, a default SMTP is no assurance of the best delivery. Therefore, it is essential to learn some other port alternatives that will better deliver your mail.

What are SMTP and SMTP Ports and their roles

SMTP is initials for Simple Mail Transfer Protocol. It is a technology used in sending emails; its role is to relay a message from the sender's server to a recipient's server. It is also known as the outgoing server.

SMTP ports are communication terminals that determine the particular location of an email address on the internet. The SMTP ports are in a domain address but are invisible to the recipient. Therefore, SMTP first needs to direct the ports to a particular address on the internet for additional processing when sending emails. Then, each email is sent to a set-out server and an SMTP port that has been chosen earlier.

There are two stages in modern SMTP transmission:

Email submission

Email submission is to put forward an email message to an outgoing server.


SMTP Relay is the process of transmitting or passing on a message between email servers (known as MTA) before getting to the recipient's server. Different ports play a role in all these stages as many times as possible.

What are the standard SMTP ports?

There are four types of standard SMTP portal, they include:

  • 25

  • 465

  • 587

  • 2525

Other ports can be used, but numerous Internet service providers prefer the above ports as a first choice. Among them, the most dependable ports are 587 and 2525. Therefore, they are used by most service providers.

The Uses of the Different SMTP Ports

Every SMTP port has a role that it plays, depending on its efficiency. Here are some purposes that different ports are for

Port 25

port 25 is the oldest of the SMTP protocols. It was used for multiple email transmissions until people started using it to send spam messages. It was misused, and people stopped using it and moved to other pots.

Even so, there are still a few people who use It. Its primary purpose is to relay email messages from one server to another.

It is not the best port for submitting emails.

Port 465

When port 25 became a transmitter, port 465 became the next secure SMTP port. Many moved to it for SSL. Later the internet assigned numbers authority --IANA- gave the port other uses and asked providers to use different ports.

In 1998 port 465 became redundant. However, it is currently in use for anyone who wants to apply implicit SSL.

Port 587

With the redundancy of port 465 in email transmission, internet authorities made port 587 the standard port for transmission. Every form of email submission was going through port 587.

Port 587 has remained relevant even up to date as it is the SMTP port which most service providers use.

Port 2525

Port 2525 is an alternative SMTP port when an error with port 587 or port 578 is unsupported by a hosting provider or an ISP. It can also play the role of an SMTP TLS port.


Finally, of the many SMTP ports, the best and the most common is port 587. If given a choice on what to settle for, you can always choose that.

If you settle for an SMTP, remember that it is crucial to run an email test before sending the email message to potential clients. You can always use mailslurp as a tool to test your email deliverability.