Two problems I encountered using Pantheon Mail in elementary OS Loki:
I am using Pantheon Mail with 3 mail accounts. Everytime I log in to elementary OS Loki mail keeps asking for passwords although the checkbox for remembering passwords is checked.
Also at startup Mail asks if the certificate of my university mail account can be trusted. I click "always trust certificate" and an error message occurs stating that there is no place to save changes for the certificate.
Thank you for your help and suggestions. If it helps I could upload a screenshot of the error message in german language.