The problem

In short, using the following line in my Exim transport does not result in the string expansion (insertion) of the TESTVAR environment variable:

headers_add = "X-TESTVAR: ${env{TESTVAR}{$value}{The TESTVAR environment variable was not found}}"

I never get $value; I always get "The TESTVAR environment variable was not found".

What am I doing wrong?

Environment:

account@example.com [~]# cat /etc/redhat-release

CentOS release 6.10 (Final)

Exim version:

account@example.com [~]# exim --version

Exim version 4.91 #1 built 11-May-2018 09:49:25

Copyright (c) University of Cambridge, 1995 - 2018

(c) The Exim Maintainers and contributors in ACKNOWLEDGMENTS file, 2007 - 2018

Berkeley DB: Berkeley DB 4.7.25: (September 12, 2013)

Support for: crypteq iconv() IPv6 PAM Perl OpenSSL Content_Scanning DKIM DNSSEC Event I18N OCSP PRDR SPF Experimental_SRS

Lookups (built-in): lsearch wildlsearch nwildlsearch iplsearch dbm dbmjz dbmnz dnsdb passwd sqlite

Authenticators: cram_md5 dovecot plaintext spa

Routers: accept dnslookup ipliteral manualroute queryprogram redirect

Transports: appendfile/maildir autoreply lmtp pipe smtp

Malware: f-protd f-prot6d drweb fsecure sophie clamd avast sock cmdline

Configure owner: 0:0

Size of off_t: 8

2019-03-08 19:04:22 cwd=/home/account 2 args: exim --version

Configuration file is /etc/exim.conf

The relevant transport from my exim.conf:

dovecot_virtual_delivery:

  driver = lmtp

  socket = /var/run/dovecot/lmtp

  batch_max = 200

  rcpt_include_affixes

  delivery_date_add

  envelope_to_add

  return_path_add

  headers_add = "X-TESTVAR: ${env{TESTVAR}{$value}{The TESTVAR environment variable was not found}}"

The commands I executed to send the email:

account@example.com [~]# export TESTVAR=hello

account@example.com [~]# echo $TESTVAR

hello

account@example.com [~]# exim -t

to:me@example.com

Hi there, this email should have a header named "X-TESTVAR" and it should have a value of "hello".

account@example.com [~]# 

The resulting email:

Return-Path: <account@host.example.com>

Delivered-To: me@example.com

Received: from host.example.com

    by host.example.com with LMTP id IH+3MCUQg1waLwAAx771+g

    for <me@example.com>; Fri, 08 Mar 2019 19:00:21 -0600

Return-path: <account@host.example.com>

Envelope-to: me@example.com

Delivery-date: Fri, 08 Mar 2019 19:00:21 -0600

Received: from account by host.example.com with local (Exim 4.91)

    (envelope-from <account@host.example.com>)

    id 1h2QLV-0004Mo-Ee

    for me@example.com; Fri, 08 Mar 2019 19:00:21 -0600

to:me@example.com

Message-Id: <E1h2QLV-0004Mo-Ee@host.example.com>

From: account@host.example.com

Date: Fri, 08 Mar 2019 19:00:20 -0600

X-TESTVAR: The TESTVAR environment variable was not found



Hi there, this email should have a header named "X-TESTVAR" and it should have a value of "hello".

You're looking for the keep_environment setting. It specifies which environment variables are trusted and should be allowed to be used within Exim's execution. (Documentation)

If your exim.conf contains this line:

keep_environment = X-SOURCE : X-SOURCE-ARGS : X-SOURCE-DIR

Change it to this:

keep_environment = X-SOURCE : X-SOURCE-ARGS : X-SOURCE-DIR : TESTVAR