View Full Version : Question about Sending Emails via Web Scripts

05-11-2005, 12:24 AM
I was curious if anyone knew about sending email using web scripts (eg. mail() in PHP, or CDONTS in ASP) and their susceptibility to spam filters. I have spent the better part of this afternoon researching the subject, but haven't been very successful in finding a satisfactory answer to my question.

I'm wondering if not setting certain header information increases the chances of an email being caught in stricter filters. The emails that are being sent from my website are text only, so I can't see it being flagged by the content of the message, unless I have a "remove" in there somewhere...

Thanks for your time!

05-11-2005, 05:24 PM
May I ask if you are attempting to send unsolicited e-mail?

05-11-2005, 07:14 PM
No, the email I am sending is not unsolicited. The site this is in reference to has a classified ad component, and a web form is used by visitors to contact the ad posters by email. We use the web form in order to hide the posters' email addresses.

We have received the odd email from ad posters who have said they have received no response through email from their posting. Some people find the emails in their spam or junk folder, and some people cannot find them at all. We log all emails sent through the site, and have confirmed (at least through the logs) that emails have been sent to them.

Is there anything we can do on our end in order to minimize the number of these emails which are being caught in spam filters?

05-11-2005, 07:31 PM
Ok, good.

I don't think using script engines to generate e-mail will be a huge issue, but you might run into a problem with sites that do reverse-DNS lookups on e-mail before it accepts the message. For example:

1. Your webserver, say, for example: generates an e-mail and initiates an SMTP session to send an e-mail to user blah@somesite.com
2. The receiving server @somesite.com will do a reverse-DNS lookup on
3. Receiving server will compare the domain from the lookup to the domain in your From & Reply-To field. If they do not match, it might be blocked.

Our company does not do this, but I know many do. We discovered this because our outbound SMTP relay didn't use to have a public DNS entry and we kept having e-mail problems because receiving servers could not verify the domain based on the public IP address.

So, if your script engine is set up to forward all e-mail to an outbound SMTP relay host, then this shouldn't be a problem, so long as your outbound SMTP relay will return the proper domain when doing a reverse lookup on its public IP address.

You also said, "I can't see it being flagged by the content of the message," however our corporate SPAM filter does just that. It has a scoring system that looks for text phrases such as "FREE SHIPPING", "GREAT OFFER", "PERSCRIPTION", "VIAGRA", you get the idea. Each phrase or anomolous condition found will increase the likelyhood that an e-mail will be stopped.

But, as long as your classified ads are not great offers for viagra in which the purchaser would receive free shipping, content probably won't be an issue. It might be a good idea, though, instead of sending the messages directly to the user@somesite.com, just send an e-mail that says "your ad has been replied to, click here to view the response" or something like that. That way, you know the e-mail content will be the same every time.