Home / server / Questions / 893648
In Process
Perrschy
Asked: 2018-01-24 01:23:33 +0800 CST

Postfix - Bad recipient address syntax - email starting with dash/hyphen

  • 772

I am trying to send an email to a recipient with an email address starting with a hyphen/dash, e.g. [email protected]

The recipient claims the mail address is correct.

mail.log shows:

postfix/smtpd[26055]: warning: Illegal address syntax from ...[...] in RCPT command: <[email protected]>

I am using Postfix 2.11.3

Any idea how I can send emails to such an address?

debian

2 Answers

  1. You can configure Postfix to accept such addresses with option allow_min_user = yes.

    The postconf documentation also explains why the default is to reject such addresses:

    Allow a sender or recipient address to have `-' as the first character. By default, this is not allowed, to avoid accidents with software that passes email addresses via the command line. Such software would not be able to distinguish a malicious address from a bona fide command-line option. Although this can be prevented by inserting a "--" option terminator into the command line, this is difficult to enforce consistently and globally.

    As of Postfix version 2.5, this feature is implemented by trivial-rewrite(8). With earlier versions this feature was implemented by qmgr(8) and was limited to recipient addresses only.

    • 1

  2. Apparently, postfix has a setting (allow_min_user) prohibiting you from sending mail to addresses starting with a hyphen due to security reasons:

    allow_min_user (default: no) Allow a sender or recipient address to have `-' as the first character. By default, this is not allowed, to avoid accidents with software that passes email addresses via the command line...

    More here: http://www.postfix.org/postconf.5.html#allow_min_user

    • 1