Broken MTA

Dear Elgg Community Developers, and Helpers,

I am running elgg Elgg 2.3.14 LTS Release  (July 24, 2019). After installing and getting the site myhotfb.com up and running for 2 months approx, I realized User on Registration were not being sent a validation email. I am running PHP 5.6.

On investigation, I found out that under basic settings  I had info-noreply@myhotfb.com setup during site installation, but in HTML Email Handler Plugin I had -f noreply@myhotfb.com setup.

So, I have corrected both the settings to noreply@myhotfb.com and with -f in  HTML Email Handler Plugin.

Flushed the site and upgraded, but still the same issue. So, I set the "$CONFIG->broken_mta = false;" to true and same issue.

My Sendmail Path: is /usr/sbin/sendmail 

Did a MTA Test using elgg script. The url is myhotfb.com/test.php

Get the following:

Attempting to email shadmujib@gmail.com...
ERROR! PHP could not deliver email to your MTA. Check that your PHP settings are correct for your MTA and your MTA will deliver email.

PHP 5.6 ini file shows

sendmail_from no value no value
sendmail_path /usr/sbin/sendmail -t -i  /usr/sbin/sendmail -t -i 

 So, experimented with values like -t -i -f noreply@myhotfb.com in HTML Email Handler still the same issue.  

Then I tried disabling HTML Email Handler Plugin and same issue. Disabled all the plugins except Bundled, same issued.

Could it be that in database respective field / table / col where the email is set incorrect? or may be core elgg file is corrupt? Can someone please help?