On Ubuntu 16.04 with postfix and Dovecot configured and working, with Roundcube installed, using Firefox, when I send an email Roundcube appears to be stuck at sending.... I can't get past the sending....
It appears that sometimes the messages do go through. Even when they do I am still stuck at the "sending" until it finally times out. If I attempt to refresh the page Firefox will warn me about leaving the page.
I'm able to receive and read messages.
When I go to settings (to set preferences) I can see the Settings and Section columns. When I click on one of the choices in the Section column, such as user interface (any actually), I get a "loading" message with the spinning circle. Nothing happens. I can make another choice from Section and the same thing happens.
When I attempted to delete a couple messages that I received I get a warning about the trash folder missing.
Further, the "About" link pops up an empty About box.
I installed Roundcube directly from the Ubuntu 16.04 repository. I've tested the servers with mail apps (Thunderbird and K-9) on both the Linux and Android. They have full functionality.
Any notions as to the cause and help would be appreciated.