Mandrill: wp_mail has been declared by another process or plugin, so you won’t be able to use Mandrill until the problem is solved.

Troubleshoot this Mandrill-related clash on your WordPress website.

The following error message may be produced if the WordPress plugin Mandrill is installed and activated while there exists another plugin on your WP setup which tinkers with the email settings on your WordPress:

wp_mail has been declared by another process or plugin, so you won't be able to use Mandrill until the problem is solved.

The Fix?

Find the culprit! This is almost certainly a WordPress plugin conflict. If you want WP Mandrill to work (to offload your transactional emails to Mandrill (the transactional email version of MailChimp FYI)), then you’ll need to fix this.

Plugins which change wp_mail to use SMTP or similar are the best place to start looking.

In our case, we didn’t have anything like this at the client website we were taking control of, so we did the following:

Step-by-Step – How to Fix This wpMandrill Plugin Conflict

1. Deactivated ALL plugins except WP Mandrill;
2. The error message disappeared (i.e. it was not a theme conflict… phew);
3. We then activated each plugin in turn, until the error message popped up;
4. In our case, it was the plugin “Scroll Triggered Box” which wasn’t even used by the website any more! We simply removed it;
5. Next we activated all other necessary plugins… everything stayed fine;
6. Finally, we added our Mandrill settings (API etc) to the relevant places and did a test to see everything worked… hooray!

What if you NEED the plugin which cause this conflict?

If you find you really need the plugin which conflicts with wpMandrill, you have 2 options: don’t use wpMandrill; or fix the plugin in question (email the plugin developer and be very nice… you never know, they might want to help you get this fixed! 😉 )

Did you Get This Fixed?!

Leave a comment below if the above helped (or didn’t help) you to get WP Mandrill working after receiving this error message. If you’re really struggling with WordPress, feel free to contact and contract us to do things on your behalf any time.