Hot answers tagged outlook
Outlook's built-in encryption uses a simple public/private key exchange scheme. In theory, all you should need to decrypt an email encrypted with Outlook's built-in encryption would be the digital ID (the sender will require your public key to encrypt, you will require the private key to decrypt), and any RFC5652-compliant email client, but as that KB ...
Your Postfix config specifies localhost (127.0.0.1) in mynetworks, which is then permitted in smtpd_relay_restrictions. This is why SquirrelMail can relay: it's sending from localhost. Since you have also specified permit_sasl_authenticated in the relay restrictions, it would appear that Outlook is not authenticating with SASL (SMTP Auth).
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