Using WebForm on my first Backdrop project. The form submission works, however when I configure to send the result via email I get an email: "Undeliverable: Form submission from: xxxxx".

In the email logs at the provider I find: "SMTP error from remote mail server after end of data: 550 Messages should have one or no Reply-To headers, not 2." 
I have tried about every permutation I can think to no avail.

Using WebForm 1.x-4.19.1 and Backdrop 1.12.1

Any suggestions?



I'll have a go at it.

In the meantime I have switched off the "Use Reply-To header" and the problem has disappeared. I am not over the moon not using reply-to, though.