Problem With E-mail & Upgrading

Oct 16, 2016
My ROM: MIUI 7 by 6.1.21 (with Italian Language)
1) I have a problem with E-mail. With WI-FI connection all E-mail arrive but without WI-FI connection E-mail don't arrive. I have set my SIM card with "data" and I can use Google search. Can be a Bug regarding E-mail?
2) I can't upgrade my Rom and in effect remain at 6.1.21. Can help me to resolve these teo problem?

I'm not able to work with my hand phone and I don't know many word as "wipe, twrp" and so. I need basic information.
Thanks for your help