Filters and the vacation responder
NOTE
Filters and the vacation responder need Viauna 0.5 or newer.
Viauna keeps each mailbox's filters and vacation responder on the mail server, as a Sieve script, the standard rule language mail servers run as mail arrives. It reads and saves the script over ManageSieve, signed in as the mailbox. So the rules work with Viauna closed, and in every mail app.
What the server needs
- ManageSieve, usually on port 4190 with STARTTLS. Dovecot has it through Pigeonhole (Mailu, mailcow and docker-mailserver include it); Stalwart and Cyrus have their own.
- These Sieve extensions, which Pigeonhole has by default:
fileinto,imap4flags(marking read, starring and labels),body(words in the message),mime(attachments),copy(forwarding),vacation,dateandrelational(the vacation responder's days),mailboxandinclude. Viauna uses only the ones a filter needs, and says which the server lacks if it can't save one. - For the vacation responder and forwarding, a way for the server to send mail (Dovecot's
submission_hostorsendmail_path; Mailu sets this up).
Setting it up
Usually nothing: Viauna connects to ManageSieve on your IMAP server's host, port 4190, with STARTTLS (or without encryption if IMAP has none), checking the same certificate name as IMAP. On a Docker network with Mailu, that's its front container, as for IMAP.
If yours is elsewhere:
| Variable | Default | |
|---|---|---|
MANAGESIEVE_HOST | IMAP_HOST | |
MANAGESIEVE_PORT | 4190 | |
MANAGESIEVE_SECURITY | starttls (none if IMAP's is) | starttls, tls or none (testing only). |
MANAGESIEVE_TLS_SERVERNAME, MANAGESIEVE_TLS_VERIFY | IMAP's | The certificate name is IMAP's only while MANAGESIEVE_HOST is unset or the same as IMAP_HOST. |
Only mailboxes on your own mail server (IMAP_HOST) have filters.
Settings > Filters shows whenever IMAP_HOST is set and FILTERS is on: Viauna doesn't check first whether the server offers ManageSieve. If yours doesn't, the tab shows the connection error and the vacation responder stays hidden; turn FILTERS and VACATION off to hide both.
On the admin page
| Setting | Variable | Default | |
|---|---|---|---|
| Filters | FILTERS | on | |
| Vacation responder | VACATION | on | |
| Forwarding in filters | FILTER_FORWARDING | off |
Forwarding is off unless you turn it on: someone who stole a session could otherwise add a filter that quietly sends a person's mail elsewhere, with no trace in their inbox. With it off, a filter that already forwards keeps working until the next time that mailbox's filters are saved, when Viauna asks for the forwarding to be removed.
Turning filters or the vacation responder off hides them in Viauna. Rules a mailbox already has keep running on the mail server until they're changed, since they live there.
How the script is kept
Viauna owns one script per mailbox, called viauna, and makes it the active one. If another script was active (Roundcube's roundcube, say), Viauna's script includes it after its own rules, so those rules keep running. When a mailbox has no filters and no vacation responder left, Viauna deletes its script and makes the other one active again.
The script starts with a comment holding Viauna's own copy of the filters, which is how it reads them back exactly. If someone edits the script by hand, Viauna notices and warns before replacing it. What each filter becomes in Sieve, and what follows from it, is in How it works: Filters.
Mailu has its own auto-reply and forwarding, in its admin pages; they run before every mailbox's script. If someone turns on both Mailu's auto-reply and Viauna's vacation responder, they'll send two replies.