Avoid Port 25 when Configuring SMTP

Modified on Thu, 21 Dec 2023 at 09:27 PM

Why Should I NOT use Port 25 when Configuring SMTP?

SMTP (standard message transfer protocol) has been around for many years as a standard method of transmitting email from one mail server to another. Historically port 25 was the only option for anyone using SMTP.

Over the years, spam became a problem. So new port options such as 587 with authentication (STARTTLS) were developed and are now preferred over port 25 which has no security. To curb spam, most ISP's and cloud hosting suppliers block email from port 25 which is the main reason why you should avoid using this port.


Tip: If your SMTP gateway is configured with port 25 (no security), then you can either:
  • Check our list of SMTP configurations for commonly used email services to see if your email service is listed and if there is another port option you can use.
  • Google to see if there are other port suggestions.
  • Contact your email service directly to see if they support other port options.
Navigation: Connect > Email Settings > Email Configuration


  • When setting your port number, ensure that you change your email settings to use the recommended port from your email provider.


Avoid using port 25 in SMTP settings in your dog walking software



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