Creating this as I found open topics on old sites with no resolution. We’re on version 3.2.6 and when we attempted to forward an email using the links within the e-mail blast, it would bring us to the page where it asks for the e-mail, then once you entered and clicked ok, it would go to a blank page and no e-mail was sent.
After an hour or so of searching for a resolution, I decided to throw it to one of our developers to take a look. After about an hour, he figured it out. In the connect.php on line 1445 he saw it was using multibyte functions which require php-mbstring to process. Upon installing php-mbstring with yum, all of the previously attempted forwarded e-mails were delivered.
php-mbstring was not in the requirements page although he said most people would install it anyways.
Hopefully this saves someone some time or maybe get that added to the requirements page.