Email filters: regex

[Alexey]

A quick summary of how to specify the "match expression" (regex) when
creating an email scan filter.
A filter is applied to email messages to find matching candidates for
importing and/or tagging.
The following message headers are examined: From:, Reply-To:, To:,
and Subject:

The matching expression is list of conditions that are AND'ed:

rto:keyword - means email address of the Reply-To: header contains
'keyword'
from:keyword - means email address of the From: header contains
'keyword'
to:keyword - means email address of the To: header contains 'keyword'
fromto:keyword - means email address of the From: OR To: headers
contains 'keyword'
subject:keyword - means subject contains 'keyword' (case insensitive)

Instead of a keyword it could be a phrase, then you need to use
quotes, i.e.
subject:"match this subject"

The '^' modifier means the match should start with the following
keyword or phrase, i.e.
to:^startKeyword

the '-' modifier means the following keyword/phrase is absent
fromto:-negativeKeyword