I'm using osTicket 1.10, PHP 5.4.16
This is driving me batty. I'm trying to enable auto-response emails for user-submitted tickets.
Auto-response emails are sent when agents create/update tickets, but not when users submit them.
I've used the diagnostic 'send email' tool - it works. I've checked the logs of our mail server - I don't see any record that the user auto-response emails are even attempted.
I'm attaching screenshots of the related settings. Any help is appreciated.
I think I've found the issue. When the customer emails arrive to the ticketing system they have a Return-Path address attached to them (in addition to the customer email address). I think the auto-responses are being sent there.
I'm still planning on upgrading, but before I did - does the current version have a way to ignore the return-path field? If not, what's the best way to do that?
Thanks for any help.
qianhe osTicket 1.10
1.10 is end of life. You should upgrade.
You have SMTP setup, but have the MTA set to PHP Mail.
Shouldn't you use SMTP since you set it up?
qianhe Auto-response emails are sent when agents create/update tickets, but not when users submit them.
You appear to have new ticket and new message disabled.
Thank you! That did it. Details, my worst nemesis.
I'll look into upgrading either today or next week.
Very welcome. 
I'll mark this as resolved and close the thread. Please feel free to start a new one if you have another question.
