Preparing an email strategy means planning for every contingency so you can conduct your send-outs without any notable issues or setbacks. A major part of this is carefully setting the right SMTP configurations to prevent deliverability issues.
Nonetheless, issues can occur from time to time despite your best preparations. In these situations, it is helpful to have an understanding of SMTP relays and the functions of ports that are associated with it, such as port 26.
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SMTP, ports, and functions What is the purpose of port 26? What is a use case for port 26? How to change your SMTP port Conclusion
SMTP, ports, and functions
To understand what port 26 is and does, one should know a bit about how SMTP works.
SMTP (Simple Mail Transfer Protocol) is the standard protocol for email exchange and is used by mail clients everywhere. Though SMTP is complex, it involves a three-stage process.
Stage 1 (submission): The user authors an email on their device, enters the recipient’s email address, and clicks the send button. This prompts the mail client to connect to an outbound SMTP server, which handles all outgoing mail.
Stage 2 (relay): The outbound server converts the email address into an IP address, then finds and connects with an inbound server using information from the DNS (Domain Name System).
Stage 3: The inbound server accepts, authenticates, and routes the incoming message to the recipient’s inbox.
For this process to function, two pieces of information are needed: an IP address, which identifies a device, and an SMTP port number, which identifies the application running on that device.
Different SMTP port assignments are used to handle SMTP relay and submission, and port 26 is most commonly used for the latter.
What is the purpose of port 26?
Unlike the more well-known ports, like ports 25 and 587, port 26 doesn’t have an assigned function. It is an alternative port that is supported by some servers.
Mail transfer agents may occasionally be permitted to use port 26 for sending outbound email messages. However, this is generally only done to circumvent issues that are occurring on another port.
What is a use case for port 26?
As previously mentioned, port 26 may be used in instances where there are issues with another port. Most commonly, port 26 functions as an alternative to port 25.
The reason for this is that many ISPs (Internet Service Providers) block port 25 as it is frequently used by spammers. Should you find that you are capable of receiving incoming messages, but are having difficulty sending outbound mail successfully, there is a strong chance that your ISP has decided to block port 25.
In this case, switching your port can help solve the issue. Preferably, you should use port 587 for submission. Port 587 is the go-to SMTP port for outbound mail and benefits from TLS (Transport Layer Security) encryption, which makes sending mail more secure. However, if you also have issues with port 587, you can switch to port 26.
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How to change your SMTP port
Fortunately, if you experience an issue sending email, changing your port settings is relatively easy. Though the exact process to change your SMTP port settings differ depending on your email client of choice, let’s use the popular Microsoft Outlook 365 as an example.
In Outlook 365, you can change your SMTP port settings by following these steps:
- Open the “File” dropdown menu.
- Click on “Info,” then “Account settings,” followed by “Manage Profiles.”
- When the pop-up window appears, click “email accounts.”
- Select the relevant account. This brings up a window called “POP and IMAP Account Settings.”
- From here, click on “More Settings.”
- Finally, go to the “Advanced” tab of the “Internet Email Settings” window. Here, you can change your SMTP port configuration.
Port 26 does not have an assigned function within the Simple Mail Transfer Protocol, so it is not often used or supported. Generally speaking, users are advised to reserve port 25 for SMTP relay and to use port 587 for SMTP submission. However, in instances where it is supported and other ports are experiencing issues, port 26 can be a useful alternative solution.