Form email not getting to some recipients

Is it the recipients' spam filtering?

[eugenebarnes]

I am testing a form-to-email contact form for one of my clients. The script is written in PHP and is set up to send email to 3 or 4 recipients plus a copy to the sender.

Two of the recipients are not getting their copies of the email. I have worked with one of the recipients trying different possible fixes including having the recipient add the email's "from" address to their address book. Still he can't get the messages.

The firm uses an internal MS mailserver for their email accounts. But the problem is only happening with two of the four recipients, so I don't consider the problem to be at the server level... at least it is less likely.

Any clues as to what might be causing the problem? Anything I can try to isolate and identify the problem?

TIA,
Eugene

[StupidScript]

Does your server's mail log show the attempts to send the messages? The successful ones and the unsuccessful ones should be right next to each other.

Also, your normal error log might show PHP errors, if

error_reporting

is turned on (i.e. add

error_reporting(E_ALL)

to the top of your script, if it's not enabled by default in php.ini).

[eugenebarnes]

Checked the mail logs after sending another test. No sign of anything other than a successful mailing at my end.

I'm wondering if something in the email headers (or something MISSING in the headers) is triggering some sort of spam filter at his end. I sent the exact same message to him from my email client and it arrived with no problems.

[StupidScript]

Sounds like you're on the right track. What headers are you sending? Also, are there any similarities between the two recipients who are not receiving the messages, like mail service or client?

[eugenebarnes]

All the recipients' email accounts are hosted in-house on a MS server under the same domain name. So I'm suspecting the problem lies with the individual's computers.

The headers sent via the PHP script are very basic (To, From, Subject, Cc). I'm wondering if certain anti-spam applications mark email as spam unless certain header information is present such as MIME info, unique message IDs, and other lines I've seen in email headers.

I'd get more specific information from the users regarding their computer configurations, but they are not very tech savvy and either don't want to be bothered too much and don't know their own computers well enough to answer my questions anyway.

The detective work continues. Thanks for your suggestions!