You do not want to do that because that can create loops.
> -----Original Message-----
> I don't want dovecot to wait X days before sending out another vacation
> response. However, setting the :days to "0" doesn't work.
>
> RFC https://www.rfc-editor.org/rfc/rfc5230.html#section-4.1 says:
>
> 4.1. Days Parameter
>
> The ":days" argument is used to specify the period in which
> addresses
> are kept and are not responded to, and is always specified in days.
> The minimum value used for this parameter is normally 1. Sites MAY
> define a different minimum value as long as the minimum is greater
> than 0. Sites MAY also define a maximum days value, which MUST be
> greater than 7, and SHOULD be greater than 30.
>
> If ":days" is omitted, the default value is either 7 or the
minimum
> value (as defined above), whichever is greater.
>
>
> If the parameter given to ":days" is less than the minimum
value,
> then the minimum value is used instead.
>
> If ":days" exceeds the site-defined maximum, the site-defined
> maximum
> is used instead.
>
> Sorry if this is more of a sieve question and is slightly off topic.