from

List mail

$ from

$ from --count

$ MAIL=[path/to/mailbox] from

$ from --sender=[me@example.com]

from [-r] [file ...]

-r
    Use Return-Path header instead of From:

file
    Input file(s) containing mail message(s); uses stdin if omitted

The from command is a lightweight utility designed to parse email messages and extract the sender's address or name from the header. Primarily used in mail processing pipelines, it reads the From: header line by default, outputting the sender information to standard output.

It processes one or more input files containing raw email messages in mbox format or reads from standard input if no files are provided. This makes it ideal for scripting tasks like logging senders in mail filters, cron jobs for mail monitoring, or integration with tools like procmail or maildrop.

The command performs simple header parsing, focusing solely on identifying the sender field. It handles standard RFC 822/2822 header formats but may not support complex MIME structures or folded headers perfectly. Output is plain text, typically the email address enclosed in quotes if present (e.g., "User ").

Common use cases include quick sender verification in shell scripts: from /var/mail/user or piping mail through it. It returns exit code 0 on success (sender found) and 1 otherwise, aiding in conditional scripting.

Performs basic header parsing; may fail on malformed or non-standard headers. Assumes mbox-like format. No support for multi-part MIME or encrypted messages.

0 if sender found, 1 if not or on error.

Conforms to traditional Unix/POSIX mail tools; not strictly POSIX-specified.

Originated in early BSD Unix mail utilities around 1980s as part of the mail(1) suite. Maintained in GNU mailutils and bsd-mailx packages; minimal changes over decades due to simple functionality.

formail(1), mail(1), munpack(1), grep(1)