What sort of features does a mail client need though? Up until recently i was using SquirrelMail and only stopped because my webhost removed it (likely because there hasn't been an official release for a few years now... which is weird since there is progress in the code repository, just not official releases). In case you haven't used it, SqurrelMail barely uses anything beyond a couple of frames (normal ones, not iframes), a table of links for the mail and a few simple controls (search, delete, mark as read, etc) with some very little (and optional) javascript for selecting all mails and stuff like that. And i really didn't miss anything using it, whereas every other web-based mail client i've seen is both slower and more annoying to use.
So, what is the use case here really, what sort of features IE11 does not provide that you'd need to implement a web-based mail client?
(note that i'm not trying to promote IE11 here, i just do not understand why IE11 would block implementing any feature to the point of dropping it entirely)
