For example for Unread Messages I use the following link:
webmail.cgi?<%url_hidden%>&do=messages-search-query&msgs_sent=&msgs_sent-opt=%3D&msgs_sent_from=&msgs_sent_from-opt=LIKE&msgs_sent_to=&msgs_sent_to-opt=LIKE&msgs_sent_cc=&msgs_sent_cc-opt=LIKE&msgs_subject=&msgs_subject-opt=LIKE&msgtrack_fid-opt=%3D&msgtrack_fid=<%msgtrack_fid%>&msgtrack_status=New&msgs_has_attach=&msgsearch_body=&mh=25&query=&sb=&so=
The real value is replaced with <%msgtrack_fid%> in the above string.
webmail.cgi?<%url_hidden%>&do=messages-search-query&msgs_sent=&msgs_sent-opt=%3D&msgs_sent_from=&msgs_sent_from-opt=LIKE&msgs_sent_to=&msgs_sent_to-opt=LIKE&msgs_sent_cc=&msgs_sent_cc-opt=LIKE&msgs_subject=&msgs_subject-opt=LIKE&msgtrack_fid-opt=%3D&msgtrack_fid=<%msgtrack_fid%>&msgtrack_status=New&msgs_has_attach=&msgsearch_body=&mh=25&query=&sb=&so=
The real value is replaced with <%msgtrack_fid%> in the above string.