Things to do when your ISP is blocking SMTP Port 25

Many ISPs are blocking what is called “Port 25” which is the port used to send e-mail, for residential broadband users all over the world. They are doing this to cut down on the amount of spam that is sent from their networks. Generally small ISPs have no idea about this, and the port 25 is open with them. By the time, the ISP realizes this, he would have already got all of his IP blocks blacklisted. Any serious ISP will always the port 25 blocked forever for residential customers. For business customers with a static IP, the ISP can enable with a proper IP declaration format.

All e-mail sent via the Internet is routed through the port 25, the channel used for communication between an e-mail client and an e-mail server. When an e-mail server that runs on your computer delivers messages, it always uses port 25 to transmit data to remote e-mail servers. Even though port 25 blocking will probably become an industry standard, however, the filter can create problems for e-mail servers and block legitimate e-mail as well as spam.
Port 25 blocking allows ISPs to block spam sent out through their networks, but it tends to punish the innocent that have a need to send through e-mail servers other than those belonging to their ISP. So, there is a workaround to make sure, you are not suffering and also not spamming at the same time.

Leased Line customers have the Port 25 open by default, as they sign IP agreement before the connection gets activated.

Here are your options :

  1. Goto your EMAIL CLIENT and enable SSL for both incoming and outgoing and then change the outgoing SMTP port to 465 or 587. If your email sending server has a valid secureĀ certificate layer, then it must work immediately. If after changing to 465 and 587 still doesnt work, then you will need to contact your email sending server admin and question him about your insecurity. That clearly means, the server admin has not bought a secure certificate for the email server and has literally exposed your emails to any kind of hackers directly or indirectly. Your emails are in danger. Be careful, and make sure, whoever is your email server provider, they must have a valid certificate in the SMTP server.
  2. You can use WEBMAIL instead of configuring the email into an application.
  3. Purchase a static IP and sign the IP agreement with your ISP, so that your ISP can allow your IP to use Port 25. And note, the ISP reserves the right to block your IP anytime, if they find spamming happening from your paid static IP as well. You will need to have your computers and devices always free from malware and virus. All the email spamming is mostly done to be malware on the windows computers of the users.
  4. If none of the above works for you, the only option left for you is to choose some small ISP from your city, who has no idea about IP blacklisting, spamming, Port 25. šŸ˜› Good luck!

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