lda: Warning: Failed to parse return-path header: Invalid character in localpart

[Christian Authmann]

Hello,
On 31.01.2018 22:35, Stephan Bosch wrote:
> Op 1/31/2018 om 6:17 PM schreef Christian Authmann:
>> Hello,
>>
>> Sometimes, when delivering mails, this warning appears in my syslog:
>>
>>> lda(...): Warning: Failed to parse return-path header: Invalid
>> character in localpart
>>
>> dovecot-lda still exits with 0 and the mail is inserted into my inbox.
>>
>>
>> Looking at the mails in question, I determined that the error is
>> caused by a multiline Return-Path header. Here's a testcase:
>>
>> --- snip ---
>> Return-Path:
>>    <nowhere at example.com>
>> From: "Nowhere" <nowhere at example.com>
>> To: redacted at example.com
>> Subject: Testcase for lda warnings
>> Date: Wed, 31 Jan 2018 12:00:00 +0000
>>
>> This is a message body.
>> --- snap ---
>>
>> Copy into a file, with \r\n line endings, then run something like this:
>>> cat testcase.txt | /usr/lib/dovecot/dovecot-lda -e -d '<username>'
>> with a username recognized by your running dovecot installation.
>>
>> The header is 'Return-Path:', \r\n, two spaces, '<...>', \r\n
>>
>> According to rfc2822 folding rules, that should be valid - the
>> Return-Path header allows CFWS at that location.
>>
>>
>> The error message originates in lib-lda/mail-deliver.c in
>> mail_deliver_get_return_address(), while the invalid character message
>> seems to originate from one of several places in lib-lda/mail-deliver.c
> 
> This is Dovecot v2.3.0 right?
> 
> Regards,
> 
> Stephan.

yes, 2.3.0 (c8b89eb), archlinux, x64. Sorry for not mentioning it earlier.

Ciao,
Christian