I have check through people facing similar issues with mail on the forum but none of them works for me. I am unable to receive email from gmail but I can send to gmail addresses.
Below is the mainlog output
Please, next time, don’t send a log as an screenshot, it’s a pain to read it 
The first thing I would do is to open ports 465 and 587 on your server, they are closed.
I have had this with gmail/google. Usually when the SSL cert has not yet been applied to web/mail. I would make sure the domain is setup as a mail domain in hestiacp then try this:
v-add-letsencrypt-domain admin example.com www.example.com yes
Make sure in hestiacp under mail domains SSL is on:
thanks for this and apologies for send screenshot. I will try this method. Howeer, I have another server with the port 587 and 465 closed but I can still send and receive mails from gmail. So not sure the port is the issue?
Closing 587 and 465 is not recommended. Gmail might get through on 25 but a lot of ISPs end up blocking 25 from time to time or permanently. Is there a reason you have those turned off?