Extract attachments from .eml file

Question

Forwarded emails are unfortunately sometimes transmitted by Outlook as .eml files, which are unusable for normal users. In particular, extracting attachments from .eml files is a challenge.

What software can extract all attachments contained in a .eml file?

Requirements:

• Free
• Open source
• Runs on Linux
• Output a file per attachment, with the intended name.
• No need to compile (binaries available, or script)
• Reasonably fast to install, I would rather avoid having to set up a particular email client program just to process this .eml file.

Answer 1

From the definition of munpack:

Unpack messages in MIME or split-uuencode format.
Munpack are utilities for encoding and decoding (respectively) binary files in MIME (Multipurpose Internet Mail Extensions) format mail messages.

To Install:

sudo apt-get install mpack

To extract the eml contents

munpack 1.eml

Answer 2

If you want to get hold of MIME parts that don't have filenames, e.g. the text and HTML, then try

sudo apt install maildir-utils
mu extract source.eml --save-all

Docs: https://manpages.debian.org/testing/maildir-utils/mu-extract.1.en.html

Answer 3

Those are all good answers, but for completeness's sake, I figured I would add more such options because some of the aforementioned tools might not be as readily available as others.

The perl-MIME-tools package includes a variety of command-line tools for processing MIME-encoded messages, including mimeexplode:

Takes one or more files from the command line that contain MIME
messages, and explodes their contents out into subdirectories of the
current working directory.  The subdirectories are just called "msg0",
"msg1", "msg2", etc.  Existing directories are skipped over. ```

The ripmime command is packaged in EPEL, if that meets your "packaged by the vendor" requirements.

This is partly taken from this Server Fault answer, links added by myself.