How to get original recipient from Postfix when using LMTP?

[MRob]

On 2019-05-22 08:18, Tuomo Soini via dovecot wrote:
> On Tue, 21 May 2019 18:24:46 +0000
> MRob via dovecot <dovecot at dovecot.org> wrote:
> 
>> Many people prefer to use LMTP for delivery from postfix for better
>> efficiency but X-Original-to header support still missing after many
>> years. One affect of this is need to set
>> sieve_vacation_dont_check_recipient = yes which violate Sieve
>> standard and cause auto-replyies sent to messages that should not
>> happen. Or abandon LMTP. or abandon postfix??
>> 
>> So while feature request is stalled are there any realistic
>> workarounds?
> 
> add to smtp_recipient_restrictions, before permitting email but after
> all checks:
> 
>     check_recipient_access pcre:/etc/postfix/recipient_access.pcre
> 
> # cat /etc/postfix/recipient_access.pcre
> /(.+)/ prepend X-Original-To: $1

Warning, do not do this unless you don't mind recipients of 
multi-recipient emails to see a list of everyone who got a copy of the 
email message, including BCC recipients. This isn't a good solution if 
you want to respect user privacy.