Plugin stopped sending after recent update

Hello,

We have been using this plugin for a long time.

It has stopped working after the latest update which was done back in November 2020.

I can see it stopped working then by looking at the logs. It worked then suddenly it stopped and all subsequent send email attempts are shown as failed in the logs.

Now when you try to send an email it says “An error has occurred when trying to send this email:”

However it doesn’t show an actual error, it only shows the a raquo.

I cannot see any settings for SMTP or anything in the options for this plugin.

I have completely removed the plugin and reinstalled the latest version just now then rebuilt the permalinks and still the error is the same.

Yes, our wordpress install can still send emails via other methods. phpmail, gravity forms etc.

Why has this plugin suddenly stopped working and how do we fix it?

Thanks,
Nicole