technique reference · by file type
Hidden text in email
An email often carries two versions of the same message, plain text and HTML, and your mail client shows only one. The other can say something different, and a model reading the raw message reads both. If an attachment is in a format we cannot open, we say so rather than calling the email clean.
The HTML half of an email is a web page, so it also gets every check we run on web pages. The techniques specific to email are below; the rest are on the web pages list.
mime.alternative-divergenceA multipart/alternative email carries two versions of one message, and this reports when the version your mail client throws away says something the version it displayed does not.mime.alternative-partThe same discarded multipart/alternative half, reported when it says nothing the displayed half did not — a disclosure that the part is there, not a claim about what is in it.mime.uninspected-attachmentA file attached to an email that this engine could not parse, named in the response rather than passed over in silence.
See also: Hidden text on web pages