Email not sending in Droplet!

Hello ,
on local development env , i setuped a sending email and its work fine with simple scenario
-enable scheduler for the site
-config sender email simply
-i send an email from one of the doc type
-it take a minute or so to reach destination (worker loaded )
-email can receive reply and add it to selected doc type

email service tested locally are Gmail and Zoho
now to my problem ,i am on the server side i made the exact same things
and even configured Gmail to open from server and add i location to accepted
tried Yahoo ,Outlock and even Yndex nothing work
used benah doctor and every thing is fine
i am using Droplet fro digitalocean can you point me to how email sended in details as possible
or an answer

@ahmad18189 seems like an issue with the background workers

ok i know the problem from the worker is there a command or action to flush or diagnose other than doctor ?