Postfix-Workaround for MS-Outlook display names problem

Microsoft Outlook has the obnoxious habit of displaying the "Display Name" portion of an email address only. That cannot be changed, whereas nearly every other mail client displays the Display Name alongside with the email address - or at least is configurable to do so.

This is important as often SPAMmers and cyber-crooks abuse this Outlook property to fake mails from IT support, CEOs etc for social engineering.

The "From:" email header with a primitively forged display name usuall looks like

From: Your companys CEO <badboy@cyber.crook>

instead of

From: Your companys CEO <ceo@your.company>

In both cases Outlook will only display Your companys CEO as sender.

If there is a Postfix mail server between your company's MS Exchange mail gateway and the internet, there is an easy way to work around the Microsoft limitations: re-format the From: line to include the mail address into the Display Name.

For this add the following line to your /etc/postfix/header_checks file (read the postfix manual how to include that into the configuration):

### workaround for Outlook - re-compose display names to include mail address
/^From:([^<]*)<([^>]*)>/ REPLACE From:$1 - $2 <$2>

which results in the From: headers to be converted into

From: Your companys CEO - badboy@cyber.crook <badboy@cyber.crook>

displayed under Outlook as Your companys CEO - badboy@cyber.crook making the fake obvious.