Looking for a regular expression which does contain a set of words

I'm trying to create a regex for my Postfix header_checks file so it will match a string that does not include .com, .net or .org domain extension.

The following regex appears to work in regex101, but fails in Postfix.

/^From: .*\.(?!(com|net|org)>)/ HOLD

All mail (including .com, .net, etc) get held in queue, and that's obviously not what I want.

I want the regex to match on strings like :

From: Example Mail <example@domain.bid>
From: Example Mail <example@domain.bid.co>

Any ideas where I am going wrong with my regex?

Solution

According to regexp_table the regular expression is matched with multi-line mode off, which implies that ^ only matches the start of the string and not the start of the line.

By default, matching is case-insensitive, and newlines are not  treated
as  special  characters. The behavior is controlled by flags, which are
toggled by appending one or more of the following characters after  the
pattern:

i (default: on)
       Toggles  the case sensitivity flag. By default, matching is case
       insensitive.

m (default: off)
       Toggle the multi-line mode flag. When this flag is on, the ^ and
       $  metacharacters match immediately after and immediately before
       a newline character, respectively, in addition  to  matching  at
       the start and end of the input string.

(By the way, I prefer "[.]" over "\." and would use a non capturing group for the alternatives: "(?:com|net|org)").