Quickly Understanding the MIME Format of Email

The format of email is MIME. A simple MIME message consists of headers followed by a body.  For example, here’s a simple text/plain email: From: sender@example.com To: recipient@example.com Subject: Example Email Content-Type: text/plain; charset=”UTF-8″ Hello, This is a simple plain text email. Regards, Sender MIME can be multipart. Here’s a text/plain email with a PDF attachment: From: sender@example.com To: recipient@example.com […]

Apple Mail warning: Unable to Verify Message Signature

If Apple Mail displays the warning “Unable to verify message signature”, and when clicking details it says: The digital signature is incorrect. The message may have been tampered with or corrupted since signed by (sender’s name). the reason is due to a bug in Apple Mail (possibly introduced in a recent version of MacOSX). See https://apple.stackexchange.com/questions/343251/apple-mail-warning-unable-to-verify-message-signature “When Mail is set […]