Add-Edit: Subject
To filter mail on the basis of the information appearing in the subject field, enter one or more words in the Subject: field. Double quotes are not allowed.
For example create an anti-spam rule and enter Free Membership in the subject field to stop any email with this phrase in the subject field from being delivered to your users.
Click Exact Match to block subjects where only these two words appear. If Exact Match is not checked, subjects containing the phrase as a part of a longer phrase, for example, "Free membership in 10,000 clubs," will also be considered a match and blocked.
See also: