Hi there @msdesignfoto,
It does indeed sound like something on your site is triggering these emails. If WP Mail SMTP is not connected to your mailer service, the emails being created won’t be able to go out. They are likely still trying though, but without a valid connection, they aren’t getting anywhere.
You mentioned that malware could be the cause. This is very possible. A lot of malware is designed to send spam emails, so it’s possible that this is what’s happening on your site. The Wordfence scan may come up with the cause but if not, you may need to go through additional troubleshooting.
You could also try disabling the other plugins on your site to see if the issue stops. If it does, it means the problem is coming from a plugin. If the problem continues, switch your theme and see if it stops. If it does, it’s the theme. If none of that stops the emails, something may have infected WordPress core files, in which case you may need to reinstall the WordPress core files or restore from a backup.
I hope that helps! Have a great day and good luck. Hopefully Wordfence can route out the cause!
Hello David
I wrote a ticket to my Service Provider and they assisted me in pinpointing out the culprit. It happens the site had a plugin to share the products through social media, and also email. They recommended the implementation of an anti-bot captcha system but as we noticed that functionality was not actually being used by costumers, I removed that plugin and enabled back WP Mail Smtp. No more trash emails have been “deliverd back” to the sender. Also, WordFence did not detect any malware whatsoever.
So problem solved. I’m just glad there was no malware and only a “backhole” allowing junk emails to be sent randomly.
Thanks for the assistance!