How to attach a file to an email using command line in RHEL 6 and later?

Solution Verified - Updated -

Environment

  • Red Hat Enterprise Linux (RHEL)
    • 6
    • 7
  • mailx

Issue

  • How can I attach a file to an email using the command line in RHEL 6?
  • Why when upgrading to mailx 12.x the way uuencoded email attachments are displayed in an email client changes from being shown as an attachment to being displayed inline?
  • Why does mailx sends uuencoded attachments as body in the mail?
  • We are not able to send the email as an attachment using the uuencode

Resolution

Either use mutt -a or mailx -a

  • mutt -a

    1. yum install mutt

    2. echo "MESSAGE BODY" | mutt -s "SUBJECT" -a "FILEPATH" "ANOTHERFILE" -- USER@DOM.TLD

      • Leave off the echo completely to enter message body interactively

  • mailx -a

    1. echo "MESSAGE BODY" | mailx -s "SUBJECT" -a "FILEPATH" -a "ANOTHERFILE" USER@DOM.TLD

      • Leave off the echo completely to enter message body interactively (press Ctrl-d when finished)

      • Skip specifying a message body by using an echo with no arguments   (echo | mailx ...)   or by dropping echo and reading /dev/null via stdin   (mailx ... USER@DOM.TLD </dev/null)

      • For sending attachments in RHEL 5, see:
        How to attach a file to an email using command line in RHEL 5?

Root Cause

There was a package change between RHEL 5 & RHEL 6. RHEL 5 had bsd-mailx, and RHEL 6 has Heirloom mailx. (That is to say, this is not a bug in uuencode but simply a change in the mailx package.)

In the newer version of mailx the headers that are used in outgoing email changed from:

~~~
From: 
Date:
To:
Subject:
~~~

to

~~~
From:
Date:
To:
Subject:
User-Agent:
MIME-Version:
Content-Type:
Content-Transfer-Encoding:
~~~

The old bsd-mailx (same as RHEL 5) package is available (unsupported) for RHEL 6 via EPEL; however, note that any scripts that require the old bsd-mailx package should be updated to use the new mailx (bsd-mailx will not be available in RHEL 7 and later)

Diagnostic Steps

  • Check the headers in the received email:
    • Email that has been sent with the old uuencode method of attachment will have a content type of Content-Type: text/plain with no boundary.
    • Email that has attachments using the newer mailx -a switch will have Content-Type: multipart/mixed; boundary="= ...." headers.

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