Php Sendmail Issue

[Viper114]

I believe it was a while ago I was looking for help with the PHP sendmail feature that I fixed by completely reinstalling sendmail in Debian. And for the longest time, it has worked with no issue with customers getting their confirmation e-mails when placing an order at our online store. However, we're now starting to get numerous contacts stating that their confirmation e-mails are not being sent out, and they have to check with us for the order info. It seems that this happens to several, but not all, people who order from us. But the kicker here is, nothing appears to be wrong with what I've done. Nothing's changed, it's exactly like it was back when I fixed it last time. AND, every time I place an order on our site to test it, I get it my confirmation e-mails, both to my work and personal e-mails. I've been advocating that it must be on the customer end, with spam filters or something stopping e-mails from coming, but now I'm starting to wonder if that's truly the case as there is turning out to be too many people to warrant ALL of them having spam filter issues. Our website is on the Amazon Elastic Compute cloud, and according to the monitoring systems they have with that, nothing really seems to be out of order with server health. As far as I can tell, everything is operating as it should. But there's too many people reporting this issue to just fully dismiss this. Is there perhaps something I haven't thought of that could be a problem?

[justsomeguy]

All you can do is verify through the server logs that PHP delivers the message to sendmail, that sendmail delivers the message to the mail server, and that the mail server sends the message out. If you can confirm that the message leaves the mail server, then it's not necessarily* an issue on your end. *Some mail servers could be blocking the mail because the sending server violates whatever polices the receiver has. Those could be things like reverse DNS lookups, SPF records, DomainKeys, etc. Check the requirements of services like Yahoo and Hotmail to see what they require from incoming mail servers.

[Viper114]

From what I can see, everything you mentioned is happening. There's no glaring errors or warnings stating anything is wrong with the overall process of PHP -> sendmail -> mail server -> out. It's just strange how so many seem to have this problem. I'm going to have our reps keep an eye out for a specific pattern and see if it's any mail services in particular that have this issue.

[Viper114]

Since we last left it, I've been trying to see if there has been a pattern to the people who are reporting not getting the e-mails. From the samples I've seen, none of them seem to have any relation to each other. Some are from Hotmail, Gmail, Yahoo and some are from private hosts. There's no clear indication of one e-mail service that is doing something to us. It's mindboggling. Everything appears to be working, and every time I try to do test orders or have someone else I know do a test order, the e-mail is received just fine. But there's still too many people reporting this issue occurring to just dismiss it. I just don't know what the actual problem is...

[boen_robot]

Is the pattern maybe all of those people doing stuff that requires emails in a particularly busy day/time?Perhaps some of the components in the chain times out without alerting the others. If that's the case, it can be cured by using a mail queue i.e. store all mails to be sent, and have a separate program take them and send them at a regular interval.PEAR packages like PEAR_Mail_Queue could likely make things easier than what you'd otherwise have to do "manually".