Apple Mail hanging up after upgrade to El Capital

[RajATL]

I am having very frustrating issues with Apple mail as it keeps hanging and drains the memory every time I open this application. Once I tun off Apple Mail computer runs fine.Not sure what is causing this issue.Has anyone faced this problem? Please help.

Also iTune keeps asking for the password everytime I start my computer.Inspite of confirming it 100 times,it still keeps asking every 10 minutes and wants me to verify my payment details as well. Please help before I go insane!!

 

[Eligos]

Open Activity Monitor and take a look at what Mail is doing. Also in Mail, toggle the "Activity" mode and check what Mail is downloading...if anything.