Friday, November 3, 2023 at 4:29 PM
After doing some tests I discovered something about our ISP (Vidéotron). On residential access, I already know inbound port 25 is blocked. No e-mails can be received. But now, I've discovered that outbound port 25 is also blocked. No e-mails can be sent. E-mails have to go through a relay SMTP server accessible on another port. That server will then send the e-mail on port 25 to its destination. We have a business account for our internet access. Port 25 is not blocked either inbound or outbound. I tried to send an e-mail on port 25 from my mom's office (on residential access) and the connection would not even open. I assume it is so zombie/hacked computers cannot send e-mails directly to their destination.