By default, 4 email recipients are considered whensuggesting filling locations for the Quick File and Browse and File options.
To change this number, use the Maximum Recipients For Suggestion option. The recommended value range is 1 to 20.
Example:
<key>Maximum Recipients For Suggestion</key>
<integer>4</integer>
Consider a scenario in which a user wants to file an email that has 6 recipients and you haven't added the Maximum Recipients For Suggestion option but set the maximum number of suggested locations to 10. These 10 suggested locations get displayed based on the filing history for emails sent or received from the first 4 recipients only, because that is the default number of recipients to consider for providing filing location suggestions.