Sendmail is responsible for sending and receiving e-mail in your VPS account via the SMTP protocol. Installing this application will allow you to send e-mail through port 2525, which is useful if your ISP has blocked you from using port 25, the default port.
For installation instructions, please click here.
Some Internet service providers (ISPs) have recently started blocking the standard sendmail port (25) to help prevent direct to MX spamming, and abuse of open proxies/relays from their dialup and broadband clients.
Unfortunately, a side-effect of this practice is that it prevents users from accessing our SMTP servers. If you are getting error messages when you try sending mail which state something to the effect that smtp.yourdomain.com is not responding or not found, contact your ISP to find out whether they are blocking port 25. If they are, you can probably send outgoing mail through their outgoing mail servers (contact your ISP to find out what outgoing mail servers you need to use).
However, sometimes an ISP will not allow e-mail to be sent through their SMTP server with a different domain. In other words, you can only use their SMT server if you have your reply address set to your ISP based e-mail address, not your custom domain name address. If this is the case, installing this site application, and configuring your e-mail client to use the alternate port will allow you to use your own custom domain name e-mail addresses.
Below is a list of some of the major ISPs that are known to block port 25. While this list is a good starting point, it is far from complete and is prone to change over time. Ultimately, the most reliable way of knowing whether your ISP is blocking port 25 is to contact them directly and ask. You can also use the How to Check if your ISP blocks SMTP guide found at the bottom of this page.
|Bell Internet High Speed (Canada)||smtp10.bellnet.ca|
|Cinncinnati Bell/Fuse Dial-up||smtp.fuse.net|
|Coax.net||smtp.west.coax.net /east / central|
|Cox||smtp.west.cox.net; smtp.central.cox.net; smtp.east.cox.net (either of the three depending on your location).|
|OOL (Optimum Online)||mail.optonline.net|
|Pacific Bell (Pacbell)||mail.pacbell.net|
|Road Runner (NYC)||smtp-server.nyc.rr.com (if outside the NYC area, please call your local Road Runner Support team)|
|Verizon||outgoing.verizon.net or smtpout.verizon.net|
if you get back 220 smtp1.arin.net . . . your ISP DOES NOT block port 25.
If your connection hangs, fails, or returns something other than smtp1.arin.net then your ISP IS blocking or redirecting port 25 to their own server.
Once you have installed this site application, you will need to configure your e-mail client to use the new alternate port. Below are some basic instructions on how to do this on a variety of popular e-mail clients, if your specific program is not listed below, you will need to contact the author of your e-mail client for specific instructions on configuring an alternate SMTP port.
Microsoft Outlook Express
Microsoft Outlook 2007
Microsoft Outlook 2003