Same issue here with the Postman SMTP plugin conflict.
Looks like they have quite a serious XSS security issue going on, bad form to mask it as a PHP “compatibility” tweak.
https://github.com/mainwp/mainwp-child/commit/64982890f66231d4543c7cbdc1407ea954da12a5
Don’t see anything that should have made wp_mail freak out though.
Plugin Author
mainwp
(@mainwp)
The support and Dev teams are currently taking a look at the issue and we should have a response / solution shortly.
@khromov The update for the security issue is listed as “Preventative: Security improvements” and admittedly was left off on the initial submit. The issue was noticed within an hour of release and the Changelog was updated before your report https://plugins.trac.ww.wp.xz.cn/changeset/1549802/mainwp-child. At the same time we also put a notice in the MainWP Usergroup and sent out an email to all our subscribers.
I appreciate you keeping us on our toes.
I have version 3.3.1 and I still get errors while using the SendGrid plugin
SendGrid: wp_mail has been declared by another process or plugin, so you won’t be able to use SendGrid until the conflict is solved.