Open “WHM”
Under “Service Configuration” , click “Exim Configuration Editor”
Click “Switch to advanced mode”

In the first editable text box below
#!!# cPanel Exim 4 Config:

ADD:

local_from_check = false
untrusted_set_sender = root

In the textbox that follows (REWRITE CONFIGURATION)
begin rewrite:

ADD:

nobody@lsearch;/etc/localdomains “${if !eq {$header_From:}{}{$header_sender:$header_From:}fail}” Fs
cpanel@lsearch;/etc/localdomains “${if !eq {$header_From:}{}{$header_sender:$header_From:}fail}” Fs

NOTE: there is no space between fai and l in the word fail above.

Now Click Save, Exim will restart with the updated config.