[Dovecot] Single instance storage

I have read most of the doc on the dovecot website, and couldn't find any info on the single instance storage feature, so I'm posting my questions here.

• Are these 3 parameters the only one necessary for single instance storage? I cannot find any doc on this feature on the website; is there anything specific I need to know about them? (the last one isn't exactly self-explanatory).

• mail_attachment_dir = /srv/vmail/attachments

• mail_attachment_hash = %{sha256}

• mail_cache_min_mail_count = 2

• Is this feature ready for production?

Thanks,

-JD