Thanks for your post @Terranista and welcome to our Community Forums.
I'm sorry to see you're getting errors in webmail.
We're aware we have issues with this we're working on getting to the bottom of, but I can't say when this will be. In the meantime, try the steps explained Here or use basic webmail Here which may improve the performance.
If those steps don't help though, I'd recommend setting up your emails on a mail client as things should be better in this way, if you're unsure how there's instructions Here. Let us know if you need further help.
If this post resolved your issue please click the 'This fixed my problem' button