These are the instructions to get the phone Mail app running on Nokia 301 or the like, read them through first, then follow every letter exactly!!!!
To activate the Mail app on your phone for Gmail:
Firstly, login to your Gmail account on a computer:
1. Enable IMAP on account settings (it might be already.). This is reached by clicking on settings, and then on the POP/IMAP tab.
2. On the far right, click on the big blue letter (usually your name initial), click on the big blue My Account, on the left choose Connected apps and sites, on the right scroll down and allow access for less secure apps.
Now, on the actual phone Mail app:
3. Choose Add account, fill in the email address, leave username blank, enter the password, choose manual setup, then choose IMAP, set Incoming port is 993, and choose SSL; outgoing is 465, SSL. Everything else should be alright.
If it doesn't work the first time, Gmail prob is blocking it still, so login on a computer and confirm activity was you!