[EXT] Support for MULTISEARCH

[Sami Ketola]

> On 10. May 2020, at 11.22, Peter <pch at myzel.net> wrote:
> 
> Am 10.05.20 um 09:54 schrieb Sami Ketola:
>>> On 10. May 2020, at 1.51, Peter <pch at myzel.net> wrote:
>>> Am 10.05.20 um 00:22 schrieb Daniel Miller:
>>>> Thank you - I'm aware of the virtual folder option and do use it. My interest is for a Windows client, EM Client, which I otherwise really enjoy. Unfortunately, they've implemented server-side searching only via MULTISEARCH - for reasons passing my understanding. So I was hoping to hear Dovecot either already had support or there were plans to implement it.
>>> 
>>> Virtual folder does not scale. Thank you for naming a client that does multisearch!
>> Virtual folder scales just fine. What makes you think it does not?
>> We have customers that have users with thousand folders and millions of emails and still virtual folder scales.
> 
> Hello Sami, I was thinking, that the client then will be overwhelmed with a mailbox of such a size?
> 
> Or does the folder start empty and only gets populated upon search with the resulting mails?

virtual folder with contents of all actual folders is usually hidden from imap clients and is used only for searching.

Sami