dovecot - Jan 2018 - lda: Warning: Failed to parse return-path header: Invalid character in localpart

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


Ciao,
Christian Authmann

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.

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