I’ve been using Roundcube for several years now and a month or more ago it started giving me a login failure notice. I submitted a help desk ticket but never got an answer.
Welcome Keith.
It will die on the end of 2019. https://help.runbox.com/roundcube/#Notice_Retirement_of_Roundcube
But it should still work now.
Hmmm,
I’m already 3 years with RunBox, and I hear for the first time about RoundCube…
We have looked into the issue and the errors are likely related to the Rouncube implementation not supporting TLS 1.2 which is now required for IMAP connections (which Roundcube relies on).
Considering the very low number of Roundcube users and our focus on Runbox 7 it’s unlikely that we will invest considerable time upgrading it or resolving the errors.
We apologize for any inconvenience caused and encourage you to get involved in the Runbox 7 development instead. 
– Geir