ISP Guide

Re: Block port 25? what does port 25 mean ?

danimallv — Mon Apr 18, 2005 11:33 pm

Author: danimallv

Posted: Mon Apr 18, 2005 11:33 pm

Another good one for port 25 unblocking is http://www.no-ip.com.

They have two services one for inbound and outbound port 25 blocking.

http://www.no-ip.com/services.php/mail/reflector Inbound
http://www.no-ip.com/services.php/mail/smtp Outbound

I've got the outbound service @ 300 msgs/day

Re: Block port 25? what does port 25 mean ?

scott — Fri Jul 02, 2004 4:50 am

Author: scott

Posted: Fri Jul 02, 2004 4:50 am

hi

If you are using port forwading(PAT) through iptables , it is possible to change the port for SMTP and other standard service running on perticular system.

i means ur current SMTP port is 25 and u r forward to any other free port.
it is realy useful for security thread.

thanks,
scott

Re: Block port 25? what does port 25 mean ?

Anonymous — Fri Jul 02, 2004 4:05 am

Author: Anonymous

Posted: Fri Jul 02, 2004 4:05 am

I use Across-Mail Service to send email out bypass the port 25 block issue of my ISP, works great. Their website is http://www.idataexpress.com

Patrick

Re: Block port 25? what does port 25 mean ?

sandeep sapru — Sun Jun 06, 2004 6:48 am

Author: sandeep sapru

Posted: Sun Jun 06, 2004 6:48 am

Roger wrote:

Hello, what the heck does it mean that my port 25 is blocked? I have a firewall, does that mean I have to remove it. I know about my computer, but when it comes to networking I dont know jack. Please help!

romeo has really made it clear port 25 is smtp port.......blame it on spammers if its blockes some crap email might have done it.

u also have a firewall can u what firewall is it?

First Understand the meaning of Port 25, then everything...

Anonymous — Fri Jun 04, 2004 4:25 pm

Author: Anonymous

Posted: Fri Jun 04, 2004 4:25 pm

is clear as glass...

What is Port 25?
Each and every Internet application, such as web, mail or ftp is assigned a unique port number by the Internet Assigned Names Authority (IANA). When a computer running mail server software starts up, it attaches to that port and uses it to listen for incoming requests. Because the port numbers are standardised across the Internet, clients can make reasonable assumptions about which port is the proper destination for a given service. When your computer needs to deliver an email to another person for example, it connects to a server on port 25 and sends the email to it. This server then sends it on to its destination. Because of the standard, you can always assume that port 25 is the SMTP mail server, not the HTTP (web) server which is port 80, or some other service.

Why do Internet Service Providers block(ISP) port 25?
Blame it on the spammers. Yes, Spammers, those some people who send you hundreds of crap emails in your hotmail account. Spammers need a way to get their spam out there and into peoples mailboxes. Most ISP's use "black lists" which list the IP addresses of known spamming organisations and common sources for spam; this provides about a 14% success rate at blocking spam. So another words, its not a good way of fighting back.

Spammers obviously know that ISP's block these IP addresses and so look for alternative ways around this and so are continually scanning IP addresses across the Internet for mail servers; when they are found, a quick test can discover if they can be used to send the spam out though; and off goes several thousand extra spam out into YOUR EMAIL ACCOUNT, haha, actually its just sent to random email accounts.

Block port 25? what does port 25 mean ?

Anonymous — Fri Jun 04, 2004 4:18 pm

Author: Anonymous

Posted: Fri Jun 04, 2004 4:18 pm

Hello, what the heck does it mean that my port 25 is blocked? I have a firewall, does that mean I have to remove it. I know about my computer, but when it comes to networking I dont know jack. Please help!