Creating mailboxes on iPhone email program

Why can I no longer create a mailbox within the iPhone email? It’s bad enough I had to delete and re-add my accounts and lost all my saved emailing to various mailboxes, now I can’t even set things back up to the way it was! I get some kind of “server error” when trying to add a new mailbox!

im trying to add a mailbox to keep track of “purchases” on my iPhone but cannot any longer! Nothing I try works any longer! Why does Comcast insist on making everything hard at times just to mess with its customers! It’s always one thing or another you guys play around with to [Edited: "Language"] people off!