Rewrite "from" for specific "to" addresses

Postfix 2.1 and above supports conditional operators within regex and pcre tables. In your case second_header_checks using these conditionals should look like this:

if !/^From:(.*)@verified-domain.com/i
/^From:(.*)/i REPLACE From: <no-reply@verified-domain.com>
endif

You can test your lookup tables without actually sending anything like this:

peter@mail:~peter $ cat msgheaders
From: <peter@external.com>
To: new@another-external.com

peter@mail:~peter $ postmap -hmq - regexp:/etc/postfix/second_header_checks < msgheaders
From: <peter@external.com>     REPLACE From: <no-reply@verified-domain.com>

peter@mail:~peter $ cat msgheaders-1
From: <peter@verified-domain.com>
To: new@another-external.com

peter@mail:~peter $ postmap -hmq - regexp:/etc/postfix/second_header_checks < msgheaders-1
peter@mail:~peter $