PHP email, contact us, send mail, but not for order confirmations

I searched the forums for this, but found nothing related.

My email transport is set to PHP, and emails are being
generated and received when originating from Contact
Us or from Send Email.

When ordering, E-mail Archive Manager shows
confirmation messages are being generated, but they
never reach the client's mailbox.

My config files do have catalog locations set to

storename.sitename.org

rather than the ususal

https://www.sitename.org/storename

Could this be the source of the problem–what's making
the PHP scripting mess up?

This started when moving between ISPs. The first had been
set to SMTP. This next ISP wants to get the PHP transport
working.

Dr Doug

When ordering, E-mail Archive Manager shows
confirmation messages are being generated
If Zen Cart is generating them, then that is the extent of which the script has control over
From there it is up to the MTA(mail transport agent) or simply said the server's email program to take it from there...
What is/was wrong with SMTP??

kobra:

What is/was wrong with SMTP??

I don't know what's wrong with SMTP. I want to see the original PHP
messages that 1) the Contact Us and Send Email scripts generate,
and that 2) the Order Confirmation Email script generates, because
that's where the line is drawn between the emails that get delivered
properly via PHP and those that disappear.

Email Archive Manager has a record of the messages, but doesn't
display their headers :( so I have no way to compare their headers
to get to the root of the problem.

I've contacted our ISP but they're not able to track the PHP outgoing
messages–only SMTP, but that's not what I'm working with at the
moment.

I am working on an SMTP solution at the moment, but that's a
topic for a different thread.

Email Archive Manager has a record of the messages
Well if ZenCart is generating them then that is all it can do as from there it is up to your MTA (mail transport agent) to deliver them