Conflict with Amelia Booking Plugin

Hi,

Our website has been using Post SMTP for a very long time, and recently acquired a new Booking System plugin called Amelia (https://wpamelia.com/).

A few days after we added the booking plugin we noticed our contact forms had stopped working, and when investigating we found that there was a redeclaration error on form submit arising from having both plugins installed.

Fatal error: Cannot redeclare Clue\StreamFilter\append() (previously declared in /home/lggraphics/public_html/wp-content/plugins/ameliabooking/vendor/clue/stream-filter/src/functions.php:17) in /home/lggraphics/public_html/wp-content/plugins/post-smtp/Postman/Postman-Mail/mailgun/vendor/clue/stream-filter/src/functions.php on line 27

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