Redux does not use the wp_mail API call. I just double checked the code base with a full search. I can only advise you contact the author of SendGrid and report it to them.
Shot in the dark: Try going into the redux-core/inc/classes/class-redux-functions-ex.php
, comment out line 587: require_once ABSPATH . '/wp-includes/pluggable.php';
and see if that solves it.
Hi @doctorofcredit – thanks for reporting this issue. We have a fix for this error and expect to update the plugin today (September 21, 2021).
In the meantime, for a temporary solution, you can take the steps mentioned by @kprovance above by going to redux-core/inc/classes/class-redux-functions-ex.php
and commenting out (or removing) line 587: require_once ABSPATH . '/wp-includes/pluggable.php';
We’ll post an update here when the update is available for download. Sorry for the inconvenience.
Chris
Redux v.4.3.1 has been deployed and it now available. Please update ASAP. THis will resolve your issue.
Thanks!
– Kev