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Discover the Power of SMTP Port 587 for Secure Email Delivery
Deliverability
SMTP: Exploring port 587
SMTP port 587 is the powerhouse behind reliable email delivery. Discover why this port is the preferred choice for secure, efficient email communication.
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When it comes to email delivery, not all SMTP ports are created equal. While port 25 might be the oldest port in the book, and port 465 had its moment in the sun, it's port 587 that specifically supports the submission of outgoing messages by end-users. If you’re managing email infrastructure, understanding the nuances of port 587 can make all the difference in ensuring your emails reach their destination.
Table of contents
Implementing SMTP and using port 587
Table of contents
A quick recap of SMTP
SMTP stands for Simple Mail Transfer Protocol. It's responsible for sending emails across networks and handles the process of sending email messages from a client to a server or between servers.
If we think of messages as ships, we can think of SMTP ports as receiving hubs. Different ports have different purposes, and some reports have better reputations than others. Here’s a high-level glance of the primary SMTP ports and their uses.
Port | Use |
|---|---|
Port | |
Port 25: The standard port | Use for non-encrypted connections. Still thought of as the standard SMTP port, most residential ISPs and hosting providers block port 25 due to heavy spam traffic. |
Use | |
Port 465: The TLS port | Use if your application or company require. Port 465 is a port that carries out message submission over Implicit TLS protocol. |
Port 587: The default submission port | Use for your business or for secure connections. Port 587 is the default SMTP port, most businesses use this port. |
Deciding which SMTP port to use is only the first step. SMTP functions off of commands and response codes, get the full breakdown in our post on SMTP commands.
The journey to port 587
SMTP ports have had an interesting history. Initially, port 25 was the go-to for email transmission and submission, but as the internet grew and email became the preferred method for delivering promotional and transactional notifications, the unsecured port 25 became a submission hub for opportunistic spammers.
Port 587 was the solution to a call for more robust and secure solutions for mail submissions. Designed to support encrypted transmission and authenticate senders, port 587 offers enhanced security features, reducing the risk of spam and improving overall email integrity. As a result, port 587 has become the standard for sending email securely, while port 25 remains primarily used for server-to-server communication.
Why port 587 is preferred
Port 587, or the submission port, is responsible for outgoing mail messages, not messages incoming to a mail server. It is a secured port, meaning it uses encryption mechanisms like STARTTLS to protect the integrity of messages.
These are the key security elements of port 587:
Authentication: Unlike port 25, port 587 requires authentication, adding an essential layer of security to your email transactions.
Encryption: Port 587 supports TLS encryption, ensuring that your email content remains confidential from sender to recipient.
TLS Encryption: Transport Layer Security (TLS) encrypts the communication channel, protecting your emails from interception.
STARTTLS Command: This command upgrades an existing insecure connection to a secure one, providing flexibility and enhanced security.
Unsure which SMTP port to use, or curious if you’re using the best one for your sending? We’ve done the deep dive on understanding SMTP ports.
Implementing SMTP and using port 587
Using port 587 isn’t rocket science, but it does require a few steps:
Step 1: Configure your email client or server to use port 587 for outgoing mail.
Step 2: Ensure that TLS is enabled to take advantage of encryption.
Step 3: Authenticate with your SMTP server using your username and password.
Common pitfalls and troubleshooting tips
Even the best-laid plans can go awry. Here are some common issues with configuring any SMTP port and how to address them:
Authentication Errors: Double-check your username and password. Ensure that your email client supports SMTP authentication.
Connection Issues: Make sure your firewall isn’t blocking port 587. Verify that your ISP doesn’t restrict access to this port.
TLS Handshake Failures: Ensure that your server’s TLS certificate is valid and properly configured.
Wrapping up
Port 587 is the modern, secure choice for email submission, offering authentication and encryption features that are essential for reliable email delivery. By understanding and implementing port 587, you can enhance the security and efficiency of your email communications.
Have questions about port 587 or other nuances of email deliverability? Our in-house email geeks have you covered.
