Sign up from the backend is sending wrong email

That is very weird and makes no sense. The signup confirmation email for both the public side and the admin side signups are generated by the email class and the subject and body template are retrieved inside of the send mail function of that class. So, there is nothing in my code that would get a different template for signups from the admin side versus the public side, since they both use the same function. The only thing I changed recently was the code that handles the template tags within the emails. I never touched anything having to do with getting the email templates themselves.

The only possible thing I can think of is that maybe it’s some persistent object cache that is somehow caching an old version of the options for my plugin, but only on the admin side. That’s a very slim possibility, but it’s the only thing I can think of at this moment that would create different emails depending on if you sign up on the admin versus the public side.

The only other thing would be a plugin, or an extension, that is tapping into the filters of the email functions and changing the message body. My Customizer extension allows you to create custom emails and assign them by sheet to the various types of emails (confirmation, reminders, etc.), but that should also affect emails from both sides. Or, maybe you had someone create something custom for you to modify the email template for specific sheets or something special? I make it very easy, with filter and action hooks all over my code, for other developers to customize things.

I would make sure to purge/reset/clear any type of caching that you have on your site and/or server, and double-check that you don’t have any extensions that are modifying emails for my plugins, or modifying the WordPress emails, that could potentially be saving an old version somehow. Double-check your email templates, and do some testing by signing yourself up from the front-end and the back-end, and see if you can reproduce it after clearing all the caches and turning off any other extensions that could possibly be causing issues.

Thanks for your reply. We cleared all caches without change.

We did some more testing and we believe this is somehow related to Volunteer Sign Up Sheets Customizer Extension. We purchased the extension several years ago so that we could have different confirmation and reminder emails for different Sign Up Sheets since some sessions are for Remote Trainings while other are for In-Person Trainings.
Even though we have a custom Confirmation email setup for a Sheet, it always send the default one from the Volunteer Sign Up Sheets Settings for signups in the backend and sends the Customizer email if signup originates on the frontend. If the Customizer plugin is disabled or enabled, the default email template is used rather than the one in the Customizer.

We tried removing the default email template and that produced no confirmation email for backend signups regardless of the Customizer being active or deactivated.

Is it possible that the Volunteer Sign Up Sheets Customizer Extension is involved in the problem? It doesn’t seem to be a matter of an old email template being cached but of the Customizer not setting the Custom Confirmation email for signups at the backend. It works correctly with signups from the front end.

Should I file this bug on the Volunteer Sign Up Sheets Customizer Extension support site?

I also tried deactivating a couple of plugins that I thought might be involved (Action Scheduler, and WP Crontrol) but the errant behaviour continued.

Is there anything else we can try?

Yes, that makes more sense now. I completely rewrote most of the Customizer extension and most likely just forgot that you may also want to send sign up confirmations emails when signing people up from the admin side (most people don’t use that feature). So, I probably only had those hooks that swap out the template on the public side. That should be a relatively easy fix, and I will push out an update later today with that fix. No need to repost on the Customizer support forum. I’ll mark this as resolved here since it’s not an issue with the main/free plugin.

Volunteer Sign Up Sheets Customizer Extension v4.0.1 fixed our problem. Thank you for the quick turnaround!