Bug#908865: exim4: Default CHECK_RCPT_REMOTE_LOCALPARTS blocks legal email addresses (in particular the % character)

[Rainer Dorsch]

Package: exim4
Version: 4.84.2-2+deb8u5
Severity: important
Tags: patch

Dear Maintainer,

I just realized that the default configuration of exim4 in Debian blocks legal email addresses with legel syntax.

E.g. list%user at gmx.de is rejected and generates a 

	restricted characters in address

entry in the rejectlog.

These email addresses are used by the most popular German email provider for distribution lists

https://hilfe.gmx.net/email/einstellungen/verteiler-anlegen.html

(I applogize for the German page, but I did not find an English version).


I changed CHECK_RCPT_REMOTE_LOCALPARTS by adding

# accept % in email addresses (local part, i.e. not domain)
# This PCRE specifies regular expressions which when matched, exim4 will reject the message
# The : seems to be a logical or
# Default
# CHECK_RCPT_REMOTE_LOCALPARTS = ^[./|] : ^.*[@%!`#&?] : ^.*/\\.\\./
CHECK_RCPT_REMOTE_LOCALPARTS = ^[./|] : ^.*[@!`#&?] : ^.*/\\.\\./

to /etc/exim4/conf.d/main/00_localconfig

I suggest to change the apply this change to the default of CHECK_RCPT_REMOTE_LOCALPARTS if there is no strong reason not to do that.

Certainly any other way to validate this legal (and probably reasonably common email addresses in Germany) is equally welcome.

Thanks
Rainer

PS: Although I would expect that this issue affects quite a few people in Germany, I did not find another matching bug report. If I missed it, please make this a duplicate.


-- Package-specific info:
Exim version 4.84_2 #1 built 10-Feb-2018 14:37:56
Copyright (c) University of Cambridge, 1995 - 2014
(c) The Exim Maintainers and contributors in ACKNOWLEDGMENTS file, 2007 - 2014
Berkeley DB: Berkeley DB 5.3.28: (September  9, 2013)
Support for: crypteq iconv() IPv6 PAM Perl Expand_dlfunc GnuTLS move_frozen_messages Content_Scanning DKIM Old_Demime PRDR OCSP
Lookups (built-in): lsearch wildlsearch nwildlsearch iplsearch cdb dbm dbmjz dbmnz dnsdb dsearch ldap ldapdn ldapm mysql nis nis0 passwd pgsql sqlite
Authenticators: cram_md5 cyrus_sasl dovecot plaintext spa
Routers: accept dnslookup ipliteral iplookup manualroute queryprogram redirect
Transports: appendfile/maildir/mailstore/mbx autoreply lmtp pipe smtp
Fixed never_users: 0
Size of off_t: 8
Configuration file is /var/lib/exim4/config.autogenerated
# /etc/exim4/update-exim4.conf.conf
#
# Edit this file and /etc/mailname by hand and execute update-exim4.conf
# yourself or use 'dpkg-reconfigure exim4-config'
#
# Please note that this is _not_ a dpkg-conffile and that automatic changes
# to this file might happen. The code handling this will honor your local
# changes, so this is usually fine, but will break local schemes that mess
# around with multiple versions of the file.
#
# update-exim4.conf uses this file to determine variable values to generate
# exim configuration macros for the configuration file.
#
# Most settings found in here do have corresponding questions in the
# Debconf configuration, but not all of them.
#
# This is a Debian specific file

dc_eximconfig_configtype='internet'
dc_other_hostnames='bokomoko.de;fdor.de'
dc_local_interfaces=''
dc_readhost=''
dc_relay_domains=''
dc_minimaldns='false'
dc_relay_nets=''
dc_smarthost=''
CFILEMODE='644'
dc_use_split_config='true'
dc_hide_mailname=''
dc_mailname_in_oh='true'
dc_localdelivery='maildir_home'
mailname:bokomoko.de

-- System Information:
Debian Release: 8.11
  APT prefers oldstable-updates
  APT policy: (500, 'oldstable-updates'), (500, 'oldstable')
Architecture: amd64 (x86_64)

Kernel: Linux 4.9.0-0.bpo.8-amd64 (SMP w/1 CPU core)
Locale: LANG=en_US.UTF-8, LC_CTYPE=en_US.UTF-8 (charmap=UTF-8)
Shell: /bin/sh linked to /bin/dash
Init: systemd (via /run/systemd/system)

Versions of packages exim4 depends on:
ii  debconf [debconf-2.0]  1.5.56+deb8u1
ii  exim4-base             4.84.2-2+deb8u5
ii  exim4-daemon-heavy     4.84.2-2+deb8u5

exim4 recommends no packages.

exim4 suggests no packages.

-- debconf information:
* exim4/drec: