dovecot - Jul 2020 - Per-user sieve_before settings?

Hi all,
I wonder if using a per-user sieve_before setting (ie: a relative path 
to user home, as ~/filter.sieve) is expected to work corretly.

Full disclaimer: I am migrating an old CentOS 6.10 box with dovecot 
2.0.9 and an old pigenhole version. I now want to redirect emails from 
old account to new account (I have a csv with old->new address pairs). 
My first approach using a single, big filter file somewhat works, but it 
is not optimal.

I am currently setting sieve_before = /var/vmail/autoreply.sieve, and it 
that file I have something as:

...
if header :contains "to" "aaa at olddomain.com"
{
         redirect "aaa at newdomain.com";
         stop;
}
if header :contains "to" "bbb at olddomain.com"
{
         redirect "bbb at newdomain.com";
         stop;
}
...

Problem is that whan an email has multiple to or cc, the filter is 
evaluated multiple times (one per recipient) and I end with multiple 
email copies on the same destination address. For example, sending and 
email to aaa at olddomain.com, cc bbb at olddomain.com is evaluated *two* 
times: when delivering the email to aaa at olddomain.com, with a 
corresponding redirect to aaa at newdomain.com, and when delivering the 
email to
bbb at olddomain.com, with *another* redirect to aaa at newdomain.com (ending 
with two email copies).

Using a per-user filter file solves the problem, as the filter is 
evaluated in the context of the right user only (ie: an email sent to 
aaa at olddomain.com, cc bbb at olddomain.com is evaluated only in 
aaa at olddomain.com context, with a corresponding single email on 
aaa at newdomain.com). However, I would avoid manipulating the already 
present per-user file (roundcube.sieve), as I need to add my custom 
rules on top of that file. Moreover, users would be able to disable the 
redirect filter.

Using a per-user before_sieve filter file seems the right solution, *if* 
it works using multiple files rather than a single global one. If not, 
do you have any other suggestion/approach to share?

Thanks.

-- 
Danti Gionatan
Supporto Tecnico
Assyoma S.r.l. - www.assyoma.it [1]
email: g.danti at assyoma.it - info at assyoma.it
GPG public key ID: FF5F32A8

Il 2020-07-10 22:20 Gionatan Danti ha scritto:
> Hi all,
> I wonder if using a per-user sieve_before setting (ie: a relative path
> to user home, as ~/filter.sieve) is expected to work corretly.
> 
> Full disclaimer: I am migrating an old CentOS 6.10 box with dovecot
> 2.0.9 and an old pigenhole version. I now want to redirect emails from
> old account to new account (I have a csv with old->new address pairs).
> My first approach using a single, big filter file somewhat works, but
> it is not optimal.
Ok, after some sleep I think to have found a better solution ;)
> I am currently setting sieve_before = /var/vmail/autoreply.sieve, and
> it that file I have something as:
> 
> ...
> if header :contains "to" "aaa at olddomain.com"
> {
>         redirect "aaa at newdomain.com";
>         stop;
> }
> if header :contains "to" "bbb at olddomain.com"
> {
>         redirect "bbb at newdomain.com";
>         stop;
> }
> ...
Simply replacing 'if header :contains ...' with 'if envelope :is
"to"
...' seems to do the trick (after adding the necessary 'require 
[...,"envelope"]') . Now emails with multiple to/cc are processed
a
single time, with no duplicates or other unexpected results. Do you have 
any other suggestion?
> Using a per-user before_sieve filter file seems the right solution,
> *if* it works using multiple files rather than a single global one. If
> not, do you have any other suggestion/approach to share?
This question remains: can someone point me to the right answer?
Thanks.

-- 
Danti Gionatan
Supporto Tecnico
Assyoma S.r.l. - www.assyoma.it
email: g.danti at assyoma.it - info at assyoma.it
GPG public key ID: FF5F32A8