Using your PCs as a mail server,
you won't be able to send-out emails to recipients
whose domain reside in ISPs that have blocked their port 25

About "Port 25" blocking

ISPs (Internet Service Providers) are blocking Port 25 because all mails sent via the Internet is routed through it. Because it is the channel used for communication between a mail client (ie: Eudora, Netscape Communicator, Outlook) and a mail server. See: Port Numbers

Port 25 blocking a method used by ISPs like: Juno, Netzero, FunCow, AT&T, MSN, etc. is one of the ways, to prevent spammers from using random ISPs to send unsolicited emails.

The problem is that, because port 25 is the default SMTP communication channel used for mails sent via the Internet between a computer and a mail server--it allows anyone to connect to; port 25 of a SMTP mail server, other than then their own--therefore, spammers can use any mail server (bypass their own) to send mass or bulk mails.
See: Open Relay

If you are using your PCs as a mail server, you won't be able to send-out emails to recipients whose domain reside in ISPs that have blocked their port 25 and return bounced mail to you with 550 error message.

The only way is to send email messages to blocked port 25 recipients is via your ISPs mail server--which no doubt, limit and restrict your access to their mail server by time or quantities of mails.

Alternatively, you can use email address from ISPs that have registered MX records addresses, for a list of Internet Service Providers that you can sign up; 

• www.emailaddresses.com 
• www.isps.com
• www.thelist.com 
• www.findanisp.com

<<back to>>     
eMail Broadcast FAQ

To top of page