Issue Duplicate php send emails

[DennyP]

CentOS Linux 7.8.2003 (Core)
Plesk 17.8.11 Update #91
php 7.3.23
postfix/Dovecot

I have several php programs called from various forms that uses the php send command to send me emails with data from the forms filled out by various people accessing my web site. The process works fine. But once in a while, I will get another copy of a email that I have already received. The copy will have a new timestamp with the current date/time, so it is not an exact copy. This only happens once in 20 or 25 emails. The duplicate comes to me anywhere between a few hours and a few days. The duplicate appears in webmail so it is not my email client (Outlook) that is creating them. They are coming from the server. The duplicate email is coming from different forms using different php programs. What could be causing this. Thanks.

 

[Bitpalast]

In order to find the cause of this symptom, please look at the mail header of the mails that seem to be duplicate. It will show the date and time when these mails were submitted to the smtp server, and it will also show the hops between the submission and the recipient's mailbox. From that information you'll be able to tell whether these are really copies and where the hold-up is for the duplicate or whether a customer might have simply clicked a button twice, hence initialized the mail twice.

 

[DennyP]

I will check the mail headers the next time it happens. It could be days or weeks.

I'm pretty sure the customer didn't click twice because the same PHP program writes the data to a file and that part is not duplicated.