Isp Smtp Port 25 Blocked

[procyon]

I use CAT hinet for ADSL and have a number of my own domains for email.

I know they have all blocked port 25 for SMTP to prevent spam and up until a few weeks ago using the server of the ISP, relay.cat.net.th worked to send.

This suddenly stopped working so I tried the DNS 202.47.249.23 which worked. Today this no longer works neither does any of their others: mail.cathinet.com , relay.cat.net.th, mail.cat.net.th , 202.47.249.4 ,

202.129.27.134

I have also tried changing the port to 587 to use my own domain to send.

Nothing works so I'm stuck without email, does anyone have any suggestions aside from changing provider?

Thanks.

[Guest Reimar]

Check out No-IP.com!

I use it for my own servers incl. E-Mail with port forwarding because my ISP blocks port 25 as well. I also use the Backup MX service from No-IP.com. For me works excelent!

[sjaak327]

I really hate it when providers do block port 25 or any other port for that matter. For me it is a sure reason to change provider. Many people actually use their provider's smtp server to do relay mail to your own mail server.

To achieve this you need two MX records in DNS, the first one (with the highest priority) should be your own SMTP server and the second one should be the SMTP server of your ISP (which of course hasn't got it's port 25 blocked !).

So your MX records should look like this:

yourdomain.com MX 10 yourmailserver.yourdomain.com

yourdomain.com MX 20 ispmailserver.ispdomain.com

Now whenever an smpt server is trying to send mail to your server, it cannot connect to the first server (port 25 is blocked), but it can reach the second server, that server is then going to find the MX records for your domain, and it will of course select the first one (your own server).

[procyon]

Thanks for the replies, I'll look into the MX records of the domains though it does seem like a bunch of hassle.

I'm surprised other people don't have this problem also, Thai ISP's are absolutely shocking, its a miracle any internet based business can survive in this country.

The problem last night was CAT's SMTP servers down, it works fine again today but I hate relying on them so will investigate your two options posted above.

Thanks again

P.

Edited February 1, 2007 by procyon