Add filter to emails sent by wp-admin/user-new.php

[johnbillion]

wp-admin/user-new.php contains a call to wp_mail() which sends an email when an existing user is invited to a site from the Users -> Add New -> Add Existing User screen within a site on Multisite. (Ref).

The contents of the email cannot be filtered. The subject, message, and headers should be passed through a filter in the same format as the password_change_email filter. (Ref).

[contact-banker]

Added patch for #42132.

It now applies filter to the contents of the email.

[anand.au14]

Added patch to add filter content of email sent on new user joining confirmation

[benoitchantre]

It would be great to add a filter for $new_user_email['subject'].

[anand.au14]

@benoitchantre Proposed patches have a filter for the array - $new_user_mail which includes To (recipient email), Subject and Message. So it will also allow filtering the subject.

[benoitchantre]

Replying to anand.au14:

@benoitchantre Proposed patches have a filter for the array - $new_user_mail which includes To (recipient email), Subject and Message. So it will also allow filtering the subject.

Great, thank you for mentioning that @anand.au14. I didn't saw it :-)

[nikolam]

Refreshed the patch. Cleared up the code a bit, made it to look more like #42133

[nikolam]

No need for unit tests for this change IMO.

[desrosj]

This ticket has not received any attention during the 5.2 cycle. With beta
1 tomorrow, going to punt this to 5.3.

[desrosj]

The patch is no longer applying cleanly and still needs review. The 5.3 beta deadline is just under 4 days away, so I am going to punt this.

If the patch is refreshed and someone has time to review before that, it can be moved back.

[anand.au14]

Added refreshed patch

[SergeyBiryukov]

Related: #42133

[johnbillion]

In 49029:

Users: Introduce the invited_user_email filter for filtering the contents of the email sent when an existing user is invited to a site on Multisite.

Props contact-banker, anand.au14, nikolam, johnbillion

Fixes #42132

[desrosj]

Let's note this new filter in the miscellaneous dev note.

[daisyo]

Dev note published: ​https://make.wordpress.org/core/2020/11/20/miscellaneous-developer-focused-changes-in-wordpress-5-6/