{"id":82318,"date":"2024-10-08T20:08:07","date_gmt":"2024-10-08T20:08:07","guid":{"rendered":"https:\/\/mailrelay.com\/glosario\/smtp-port\/"},"modified":"2026-10-06T22:05:42","modified_gmt":"2026-10-06T22:05:42","slug":"smtp-port","status":"publish","type":"glossary","link":"https:\/\/mailrelay.com\/en\/glossary\/smtp-port\/","title":{"rendered":"SMTP port"},"content":{"rendered":"\n

An SMTP port is the connection number a program uses to send email to a server with the SMTP protocol.<\/strong> The most common ones are 25, 465, 587 and 2525.<\/p>\n\n

Think of an office building. The server address is the street and number; the port is the specific door you walk through. If you pick a locked door, the email doesn’t go out.<\/p>\n\n

To send email from a website, an app or an email client, use 587 or 465.<\/strong> Port 25 is reserved for communication between servers.<\/p>\n\n

What is an SMTP port?<\/h2>\n\n

SMTP<\/a> is the protocol email uses to travel across the internet. Each server listens on one or more ports, and your app has to connect to the right one.<\/p>\n\n

The port also determines how the connection is protected. Some encrypt from the start, others encrypt after greeting the server, and some can work without encryption.<\/p>\n\n

That’s why, when you set up a WordPress plugin, a CRM or an email client, you’ll always be asked for four details: server, port, username and password.<\/p>\n\n

What are the SMTP ports and what is each one for?<\/h2>\n\n

These are the four you’ll come across:<\/p>\n\n

Port<\/th>Encryption<\/th>What it’s used for<\/th>Is it usually blocked?<\/th><\/tr><\/thead>
25<\/td>Optional (STARTTLS)<\/td>Sending between mail servers<\/td>Yes, on many home networks and in the cloud<\/td><\/tr>
465<\/td>TLS from the start (SMTPS)<\/td>Sending from apps and email clients<\/td>No<\/td><\/tr>
587<\/td>STARTTLS<\/td>Sending from apps and email clients<\/td>No<\/td><\/tr>
2525<\/td>STARTTLS or TLS<\/td>Alternative when 587 is blocked<\/td>No, but not every provider offers it<\/td><\/tr><\/tbody><\/table><\/figure>\n\n
\"The<\/figure>\n\n

Port 25<\/h3>\n\n

It’s the original SMTP port, from 1982. Today servers use it to deliver email to each other.<\/p>\n\n

Many internet and cloud providers block it to curb spam<\/strong> sent from infected machines. If your app can’t send through port 25, this is almost always why.<\/p>\n\n

Port 465<\/h3>\n\n

It encrypts the connection with TLS from the very first moment. It was deprecated in 1998, but RFC 8314 (2018) brought it back as a recommended option for sending email.<\/p>\n\n

It’s a good choice if your provider supports it and your program lets you choose “SSL\/TLS”.<\/p>\n\n

Port 587<\/h3>\n\n

It has been the standard submission port since 1998. The connection starts unencrypted and switches to encrypted with the STARTTLS command.<\/p>\n\n

It’s the one almost every provider supports<\/strong>, so it’s the safest bet if you don’t want to get it wrong.<\/p>\n\n

Port 2525<\/h3>\n\n

It isn’t an official port, but many SMTP services offer it as an alternative. It comes in handy when your network or your hosting blocks 25 and 587.<\/p>\n\n

Which SMTP port should I use?<\/h2>\n\n

Use 587 with STARTTLS or 465 with SSL\/TLS.<\/strong> Both encrypt the sending and require a username and password.<\/p>\n\n

Choose based on what your provider asks for:<\/p>\n\n

Situation<\/th>Recommended port<\/th><\/tr><\/thead>
You’re setting up a website, a CRM or an app<\/td>587 (or 465)<\/td><\/tr>
Your program only offers “SSL\/TLS”<\/td>465<\/td><\/tr>
Your network blocks 587<\/td>2525, if the provider offers it<\/td><\/tr>
You run your own mail server that delivers to other servers<\/td>25<\/td><\/tr><\/tbody><\/table><\/figure>\n\n

Avoid sending without encryption. Besides exposing your password, many providers no longer accept connections without TLS.<\/p>\n\n

SMTP server and port for Gmail, Outlook and other providers<\/h2>\n\n

These are the settings for the most common providers:<\/p>\n\n

Provider<\/th>SMTP server<\/th>Port<\/th>Encryption<\/th><\/tr><\/thead>
Gmail<\/td>smtp.gmail.com<\/td>465 or 587<\/td>SSL\/TLS or STARTTLS<\/td><\/tr>
Outlook.com and Hotmail<\/td>smtp-mail.outlook.com<\/td>587<\/td>STARTTLS<\/td><\/tr>
Microsoft 365<\/td>smtp.office365.com<\/td>587<\/td>STARTTLS<\/td><\/tr>
Yahoo Mail<\/td>smtp.mail.yahoo.com<\/td>465 or 587<\/td>SSL\/TLS or STARTTLS<\/td><\/tr>
Mailrelay<\/td>smtp1.s.ipzmarketing.com<\/td>587<\/td>STARTTLS<\/td><\/tr><\/tbody><\/table><\/figure>\n\n

Watch out for passwords.<\/strong> Gmail and Microsoft are phasing out regular passwords in third-party apps: they’ll ask you for an app password or for signing in with your account (OAuth).<\/p>\n\n

These servers have daily limits for sending in volume. A professional SMTP service<\/a> is built for that.<\/p>\n\n

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Send your website and store emails with Mailrelay<\/strong><\/p>\n\n\n\n

Connect your website via SMTP or API and track deliveries, opens, clicks and bounces in real time. Try it free for 30 days.<\/p>\n\n\n\n

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Try SMTP for free<\/a><\/div>\n<\/div>\n<\/div><\/div>\n\n

SMTP, IMAP and POP3 ports<\/h2>\n\n

SMTP is only for sending.<\/strong> To receive email in your program, IMAP<\/a> or POP3<\/a> are used, each with its own ports:<\/p>\n\n

Protocol<\/th>What it’s for<\/th>Encrypted port<\/th>Unencrypted port<\/th><\/tr><\/thead>
SMTP<\/td>Send<\/td>465 or 587<\/td>25<\/td><\/tr>
IMAP<\/td>Read and sync the mailbox<\/td>993<\/td>143<\/td><\/tr>
POP3<\/td>Download email<\/td>995<\/td>110<\/td><\/tr><\/tbody><\/table><\/figure>\n\n

If your program receives but doesn’t send, the problem is almost never IMAP or POP3: check the SMTP server and port.<\/p>\n\n

How to tell if an SMTP port is blocked<\/h2>\n\n

If the app gets stuck “connecting” and ends with a timeout error, try this:<\/p>\n\n

    \n
  1. Switch ports.<\/strong> If 587 fails, try 465 or 2525.<\/li>\n\n\n\n
  2. Try from another network.<\/strong> If it works on mobile data, the block is on your network or your hosting.<\/li>\n\n\n\n
  3. Check the connection.<\/strong> In the terminal, telnet server 587<\/strong> should reply with a greeting that starts with 220.<\/li>\n\n\n\n
  4. Ask your provider.<\/strong> Some hosting and cloud services only open 25 or 587 if you ask.<\/li>\n<\/ol>\n\n
    \"What<\/figure>\n\n

    Common mistakes when setting up the SMTP port<\/h2>\n\n

    The most common one is mixing up port and encryption:<\/strong> 465 with STARTTLS or 587 with SSL. The connection fails even though the details are correct.<\/p>\n\n

    Other common mistakes are using port 25 from a website or an app and mistyping the server. It also often happens that people use their email password when the provider asks for an app password.<\/p>\n\n

    And remember that the port alone isn’t enough to reach the inbox. Deliverability<\/a> also depends on authenticating your domain with SPF<\/a>, DKIM<\/a> and DMARC<\/a>.<\/p>\n\n

    Mailrelay’s SMTP port<\/h2>\n\n

    If you use Mailrelay<\/a> for your transactional emails<\/a>, connect your app to the server smtp1.s.ipzmarketing.com on port 587. You’ll find the username and password in your account.<\/p>\n\n

    Also set up authentication with the sending domain<\/a> guide. That way your emails go out signed with your domain and you’ll see deliveries, opens, clicks and bounces in real time.<\/p>\n\n

    SMTP is included in the Standard and Enterprise plans. On the free account you can try it for 30 days and then add it for \u20ac14.95 a month. And if something won’t connect, support will help you via chat, ticket or phone.<\/p>\n\n

    \n

    An SMTP service with real support<\/strong><\/p>\n\n\n\n

    SMTP and API included in Standard and Enterprise, with chat, ticket and phone support on every plan.<\/p>\n\n\n\n

    \n
    Create a free account<\/a><\/div>\n<\/div>\n<\/div><\/div>\n\n

    Frequently asked questions about the SMTP port<\/h2>\n\n

    These are the most common questions.<\/p>\n\n

    What is port 587?<\/h3>\n\n

    It’s the standard port for sending email from an app or an email client. It uses STARTTLS to encrypt the connection and requires a username and password.<\/p>\n\n

    Is port 465 or 587 better?<\/h3>\n\n

    Both are secure. Port 465 encrypts from the start and 587 encrypts with STARTTLS. Use the one your provider tells you to; if it supports both, either will do.<\/p>\n\n

    What is port 25 used for?<\/h3>\n\n

    For mail servers to deliver messages to each other. Don’t use it to send from a website or an app: it’s usually blocked.<\/p>\n\n

    Which SMTP port uses SSL?<\/h3>\n\n

    Port 465. It’s the SMTP over SSL\/TLS port, also called SMTPS, and it encrypts the connection from the very first moment.<\/p>\n\n

    What is Gmail’s SMTP port?<\/h3>\n\n

    The server is smtp.gmail.com, with port 465 (SSL\/TLS) or 587 (STARTTLS). You’ll need an app password if your account has 2-Step Verification turned on.<\/p>\n\n

    Related entries<\/h2>\n\n