SMTP, or Simple Mail Transfer Protocol, is an Internet standard protocol used for sending and receiving email, although most applications use it exclusively for sending email.
SMTP communication between email servers typically uses the TCP (Transfer Control Protocol) port 25 – think of this as the “channel” used for sending email between servers.
However, to reduce the amount of spam email being sent from their networks, many ISPs (Internet Service Providers) automatically block communications on port 25. As a result, emails sent by applications configured to use port 25 will be rejected.
Resolving the Port 25 Blocked error
To ensure your email is not rejected, you should configure your mail applications to use an alternative port for outgoing messages, such as 26, 465 or 587. For HostPapa Basic and Advanced POP or IMAP email services, you should configure your email application to use port 465 for outgoing messages.
Find out more about configuring email applications in the following knowledge base articles:
- How to set up a POP/IMAP email account in Microsoft Outlook 2016
- How to set up a POP/IMAP email account in Microsoft Outlook 2013
- How to set up email in Outlook 2016 for Mac
- How to configure a POP3 account in Apple Mail
- How to set up your email on Android
If you notice any problems or if you need any help, please open a new support ticket from your HostPapa Dashboard. More details on how to open a support ticket can be found here.