Subscribe by email - featured image size

Hi,

Trying to change the featured image size in the email template. I found a previous ticket suggesting that editing the plugin file > subscribe-by-email/inc/mail-templates/mail-template.php would do the trick.

It doesn't seem to have any effect on this site.

The theme uses blog post featured images at 650 x 275px and they look terrible when cropped to the default 150 x 150px.

Be great if you could point me in the right direction. Cheers!

Ken