The use of a variable substitution erroneously produced a runtime syntax error.

Also check the X-Sieve-Redirected-From header for our own e-mail addresses. This
header is added by the redirect action itself and in a mail loop it would see
that same header with that same content. This is less reliable than the other
mail loop detection (sender may set such a header), so, unlike the existing loop
detection based on the duplicate db, the implicit keep is not canceled when the
new loop detection is triggered.

test suite: enotify extension: Add tests for interaction between ":encodeurl" and variable size limits.

It is a remnant from debugging.

It erroneously applied another layer of MIME header encoding.
The problem is that existing Sieve scripts may rely on this behaviour; i.e. scripts may contain addresesses with literal UTF8 in the phrase part.
Therefore, this change allows both behaviors.

Now using struct smtp_address rather than sieve_address.
In some cases, struct message_address may prove to be more suitable, but this is the best fit for now.
Adjusted to the renamed fields in struct mail_deliver_context.

lib-sieve: redirect action: Always set X-Sieve-Redirected-From header to sieve_user_email if configured.

Set it to the final recipient only when there is an envelope and sieve_user_email is unconfigured.

lib-sieve: vacation extension: Allow ignoring the envelope sender while composing the "To:" header for the reply.

This adds a new setting "sieve_vacation_to_header_ignore_envelope".
With this setting enabled, the "To:" header is always composed from the first "Sender", "Resent-From" or "From" header found in the message (in that order).
Normally, the "To:" header is composed from the address found in the "Sender", "Resent-From" or "From" headers that is equal to the envelope sender.
If none is then found, the bare envelope sender is used.
The new setting allows ignoring the envelope, which is useful e.g. when SRS is used.

lib-sieve: vacation extension: Compose the "To:" header from full sender address found in the first "Sender:", "From:" or "Resent-From:" header.

Before, it would create a "To:" header without a phrase part. The new behavior is nicer, since the reply will be addressed to the sender by name if possible.
This addresses an old FIXME.

lib-sieve: vacation extension: Use Microsoft X-Auto-Response-Suppress header to prevent unwanted responses.

We've seen a few situations where Pigeonhole and Microsoft products start a useless machine conversation.
At least older versions of Outlook ignore the standards on multiple points to make this happen.
We prevent this now by recognizing and generating the X-Auto-Response-Suppress header.

lib-sieve: vnd.dovecot.report extension: Added Dovecot-Reporting-User field, which contains the e-mail address of the user sending the report.

lib-sieve: vnd.dovecot.report extension: Added support for configuring the "From:" address used in the report.

A "vnd.dovecot.config.<identifier>" environment item maps to the content of the matching sieve_env_<identifier> plugin setting.

lib-sieve: vacation extension: The sieve_user_email setting is now used in check for implicit delivery.

This means that vacation responses are now also sent for messages that include the sieve_user_email address in one of the relevant headers.

The recipient_delimiter is treated as multiple one-character delimiters
rather than one multi-character delimiter if more than one character is
supplied.

Based on a patch by: Lennart Weller <lhw@ring0.de>

This is used mainly when no other means of obtaining the user's email is available, such as when there is no envelope (in IMAP).
Before, the postmaster address or the null "<>" address was used as a fallback for sending messages.
The redirect and enotify commands can be explicitly configured to use what is configured with sieve_user_email.

lib-sieve: Made sure local part of a mail address is encoded properly using quoted string when it is not a dot-atom.

Registering conflicting commands before conflicts are checked is a bad idea.
Make sure conflicting extensions are not part of remaining validation process.

It allows sending feedback report (RFC 5965) messages.

lib-sieve: util: program-client-local: Changed link between parent and child process from a socketpair to a double pipe.

Turns out /dev/stdin, /dev/stdout, and /dev/fd/XX don't work on Linux if the underlying FD is a socket.
Since some programs may rely on those symbolic links to work, the local client is amended to use two pipes instead.
This will not help for programs invoked in the remote script service, since a socket is required for the connection.