Try going to the var subfolder in your revive installation. There you can find a file your.domain.here.conf.php.
For me things started to work when I set the option requireSSL=1.
Oh, and have you checked that your https page only uses banners provided through https? Firefox does not load "acitve mixed content" since Firefox 23 so if you put your banners on ...
Via the Open-Xchange webmail user interface, you can download a .zip file containing multiple emails by doing the following:
Mark the checkbox next to each email you want to include in the .zip file
Click the menu icon above the list of emails
Click the "Save as file" link
Your web browser will then display its "Save as..." dialog, which you can use to ...