Post-login script on proxy side

[Sami Ketola]

> On 12 Jul 2017, at 10.36, azurit at pobox.sk wrote:
> 
> Backends don't have access to user database and i wanted to keep it like this :(

Then probably your only possibility is to update last_login information with the authentication
policy framework introduced in dovecot 2.2.25: https://wiki2.dovecot.org/Authentication/Policy

just build your custom auth policy server that updates last_login information after successfull
passdb authentication

Sami