When creating a filter for an automatic answer to emails, it it not possible to add an attachment to this automated email.
One can add an attachment (i.e. PDF) to an email which is created by a filter rule.
There is customers that need to be able to send out some documents in an automated fashion and therefore require this feature.
RFC5230 defines a :mime parameter for vacation action. We need to add support for this in the parser and the UI. The attachment would need to be stored inside the sieve script which will have some performance impact. The managesieve implementation may limit the total script size which can be a problem.