Technical Support

Are You Getting Bounced E-Mail To Specific Recipiants?

Some individuals who have their own mail server operating on a dynamic IP address sometimes encounter a specific situation. They find that sometimes their email messages are delivered to some recipients but refused by the email server of other recipients. One of the reasons that this occurs is that some ISP's such as AOL, Earthlinlk, and others, try to protect their subscribers from receiving unsolicited SPAM. One way to accomplish this is to verify that the sender is legitimate by performing a "reverse lookup." Here's how that works.

When you send an email message and your mail server completes the connection with the receiving server it tells the receiving server your current IP address. This is part of the SMTP protocol (Simple Mail Transfer Protocol). Your IP address that your server reported "belongs" to your ISP and it was temporarily assigned to you by your ISP. The receiving server performs a "reverse DNS lookup" on your IP address to determine the domain name associated with that address. (Commonly a DNS lookup starts with the domain name and then finds the associated IP address. The "reverse DNS lookup" starts with the IP address and finds the domain name.) It finds that the domain name associated with that IP address is the domain name of your ISP.

Next your server sends a "HELO" message to the receiving server and that message contains your domain name. The receiving server compares the domain name it discovered through performing the "reverse lookup" with the domain name your server sent. When these two domain names are not the same then the receiving server assumes that the email message is SPAM and rejects it. Not all receiving servers perform the "reverse lookup" so your email may be rejected in some cases but not all cases.

To solve this problem you should send your email out through your ISP's server, not yours. To accomplish that you need to know the IP address of your ISP's server and you can find that by contacting your ISP. Some of our customers have told us that their ISP wasn't immediately forthcoming with that information but they were able to get the IP address by explaining that they needed it to configure Outlook for use with the free email account that the ISP offers and to accomplish that they need the ISP mail server's IP address. In many cases sending mail through your ISP will solve the problem sending email from a dynamic IP address.

For more information or to post questions or comments about the use of our products please visit our Online Support Forum.

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