--- a/init.h
+++ b/init.h
@@ -295,6 +295,9 @@ struct option_t MuttVars[] = {
   ** .pp
   ** When this variable is set, mutt will include Delivered-To headers when
   ** bouncing messages.  Postfix users may wish to unset this variable.
+  ** .pp
+  ** \fBNote:\fP On Debian systems, this option is unset by default in
+  ** /etc/Muttrc.
   */
   { "braille_friendly", DT_BOOL, R_NONE, OPTBRAILLEFRIENDLY, 0 },
   /*
@@ -825,6 +828,9 @@ struct option_t MuttVars[] = {
   ** one is not used.
   ** .pp
   ** Also see ``$$use_domain'' and ``$$hidden_host''.
+  ** .pp
+  ** \fBNote:\fP On Debian systems, the default for this variable is obtained
+  ** from /etc/mailname when Mutt starts.
   */
   { "ignore_linear_white_space",    DT_BOOL, R_NONE, OPTIGNORELWS, 0 },
   /*
@@ -1338,6 +1344,9 @@ struct option_t MuttVars[] = {
   ** system.  It is used with various sets of parameters to gather the
   ** list of known remailers, and to finally send a message through the
   ** mixmaster chain.
+  ** .pp
+  ** \fBNote:\fP On Debian systems, this option is set by default to
+  ** ``mixmaster-filter'' in /etc/Muttrc.
   */
 #endif
 
@@ -1887,6 +1896,10 @@ struct option_t MuttVars[] = {
   ** This variable contains the name of either a directory, or a file which
   ** contains trusted certificates for use with OpenSSL.
   ** (S/MIME only)
+  ** .pp
+  ** \fBNote:\fP On Debian systems, this defaults to the first existing file in
+  ** the following list: ~/.smime/ca-certificates.crt ~/.smime/ca-bundle.crt
+  ** /etc/ssl/certs/ca-certificates.crt.
   */
   { "smime_certificates",	DT_PATH, R_NONE, UL &SmimeCertificates, 0 },
   /*
@@ -2093,6 +2106,9 @@ struct option_t MuttVars[] = {
   ** certificates are also automatically accepted.
   ** .pp
   ** Example: set ssl_ca_certificates_file=/etc/ssl/certs/ca-certificates.crt
+  ** .pp
+  ** \fBNote:\fP On Debian systems, this variable defaults to the example
+  ** mentioned. This file is managed by the ``ca-certificates'' package.
   */
 # endif /* USE_SSL_GNUTLS */
 #endif /* defined(USE_SSL) */
@@ -2683,6 +2699,9 @@ struct option_t MuttVars[] = {
   ** .pp
   ** You may optionally use the reverse- prefix to specify reverse sorting
   ** order (example: set sort=reverse-date-sent).
+  ** .pp
+  ** \fBNote:\fP On Debian systems, this option is set by default to
+  ** ``threads'' in /etc/Muttrc.
   */
   { "sort_alias",	DT_SORT|DT_SORT_ALIAS,	R_NONE,	UL &SortAlias, SORT_ALIAS },
   /*
@@ -3100,6 +3119,9 @@ struct option_t MuttVars[] = {
   ** is set to deliver directly via SMTP (see ``$$smtp_url''), this
   ** option does nothing: mutt will never write out the BCC header
   ** in this case.
+  ** .pp
+  ** \fBNote:\fP On Debian systems, exim4 and postfix strip BCC headers by
+  ** default. The above warning applies to exim3 users, see /etc/Muttrc.
   */
   {"xterm_icon",       DT_STR,   R_BOTH, UL &XtermIcon,  UL "M%?n?AIL&ail?"},
   /*