Why can't I send email? Please help! (LG G3)

[AC Question]

I've seen this problem posted on a few other sites but none with solutions.

On the 14th Jan (5 days ago) email stopped sending from the built-in email app on my LG G3.

Gmail (APP) email still works (send and receive).
I can still RECEIVE email to the built in email app.

BUT I cant send email on the built in app.

I type the email, press send, and it disappears. It doesn't go to sent or outbox. Just vanishes.

I have synced all the accounts manually (all of them - this applied to all emails I have through the built-in email app). Nada.

Help greatly appreciated.

 

[iloz]

I hope you get a fix from somewhere and I get some ideas for my problem which is exactly the opposite to yours: I can use the email app.,but the Gmail app.is not