Annoying email autofill successfully been solved this afternoon (been a long battle and very irritating).
Not clearing by "clear data", " clear cache", not uninstalling Emai app, NO NO NO! They won't work!
Simply:
Go to Phone Contact > down right bottom there are 3 dots > Filter >
You will see there are many social apps under "Display Contacts", like Viber, ICQ, Wechat, Local Contact, Whatsapp, Facebook, Yahoo, Google, Skype etc.
click each of them out, and tick ALL boxes, then click "Done"
Go back to the Phone Contact, you'll find there are quite a lot unwanted contacts. Some contacts simply just with email addresses. They have all been filtered and unseen until you have just filtered them out, allowing them to be seen.
So now you could easily find those " annoying email autofill email addresses" in the Contact, simply DELETE them. I found I have like over 20 contacts under the same email addresses, same contact names too.
A baby shop email address which I accidentally added before. It has been saved under my personal email address, that's insane! (but it wasn't in my email contact list if I open my email in computers. It's only been saved in my Android phone) So whenever I wanna send email to myself , the autofill sends to that baby shop! It made me crazy and I was unable to solve it because the Contact filtered out email addresses and I didnt realise I had actually saved somewhere.
Now I have figured it out and hope it will help people out there. ( since I noticed many people couldnt solve this issue)
Cheers!