Syntax error while using valid email in sent to field

Hi there!

Been using your plugin for year now. Love it!

I’m working on this new website I just pushed live this week. Didn’t encounter any troubles on my local server nor the dev one. Though, on the live server, I can’t get the configuration to accept a valid “send to” email address. I always get the “Invalid mailbox syntax is used” error message.

Note that I’m not using a shortcode here. I’m inputting the “[email protected]” valid email address, no name, no opening or closing tags. Just the email.

I’m dumbfounded.

Please help.

Have a good one!

The page I need help with: [log in to see the link]