+All names of variables and functions may be tested. Additionally, the
+following compile-features may be tested when prefixed with 'feature_':
+ncurses, slang, iconv, idn, dotlock, standalone, pop, nntp, imap, ssl,
+gnutls, sasl, sasl2, libesmtp, compressed, color, classic_pgp,
+classic_smime, gpgme, header_cache.
+
+Examples follow.
+
+To only source a file with IMAP related settings only if IMAP support is
+compiled in, use:
+<tscreen><verb>
+ifdef feature_imap 'source ~/.mutt-ng/imap_setup'
+# or
+# ifdef imap_user 'source ~/.mutt-ng/imap_setup'
+# or
+# ...
+</verb></tscreen>
+
+To exit mutt-ng directly if no NNTP support is compiled in:
+<tscreen><verb>
+ifndef feature_nntp 'push q'
+# or
+# ifndef newsrc 'push q'
+# or
+# ...
+</verb></tscreen>
+
+To only set the <ref id="imap_mail_check"
+name="<$imap_mail_check"> when the system's SVN
+is recent enough to have it: