-(defvar notmuch-show-message-begin-regexp "\fmessage{")
-(defvar notmuch-show-message-end-regexp "\fmessage}")
-(defvar notmuch-show-header-begin-regexp "\fheader{")
-(defvar notmuch-show-header-end-regexp "\fheader}")
-(defvar notmuch-show-body-begin-regexp "\fbody{")
-(defvar notmuch-show-body-end-regexp "\fbody}")
-(defvar notmuch-show-attachment-begin-regexp "\fattachment{")
-(defvar notmuch-show-attachment-end-regexp "\fattachment}")
-(defvar notmuch-show-part-begin-regexp "\fpart{")
-(defvar notmuch-show-part-end-regexp "\fpart}")
-(defvar notmuch-show-marker-regexp "\f\\(message\\|header\\|body\\|attachment\\|part\\)[{}].*$")
-
-(defvar notmuch-show-id-regexp "ID: \\(.*\\)$")
-(defvar notmuch-show-tags-regexp "(\\([^)]*\\))$")
+(defvar notmuch-show-signature-regexp "\\(-- ?\\|_+\\)$"
+ "Pattern to match a line that separates content from signature.
+
+The regexp can (and should) include $ to match the end of the
+line, but should not include ^ to match the beginning of the
+line. This is because notmuch may have inserted additional space
+for indentation at the beginning of the line. But notmuch will
+move past the indentation when testing this pattern, (so that the
+pattern can still test against the entire line).")
+
+(defvar notmuch-show-signature-lines-max 12
+ "Maximum length of signature that will be hidden by default.")
+
+(set 'notmuch-show-message-begin-regexp "\fmessage{")
+(set 'notmuch-show-message-end-regexp "\fmessage}")
+(set 'notmuch-show-header-begin-regexp "\fheader{")
+(set 'notmuch-show-header-end-regexp "\fheader}")
+(set 'notmuch-show-body-begin-regexp "\fbody{")
+(set 'notmuch-show-body-end-regexp "\fbody}")
+(set 'notmuch-show-attachment-begin-regexp "\fattachment{")
+(set 'notmuch-show-attachment-end-regexp "\fattachment}")
+(set 'notmuch-show-part-begin-regexp "\fpart{")
+(set 'notmuch-show-part-end-regexp "\fpart}")
+(set 'notmuch-show-marker-regexp "\f\\(message\\|header\\|body\\|attachment\\|part\\)[{}].*$")
+
+(set 'notmuch-show-id-regexp "\\(id:[^ ]*\\)")
+(set 'notmuch-show-depth-regexp " depth:\\([0-9]*\\) ")
+(set 'notmuch-show-filename-regexp "filename:\\(.*\\)$")
+(set 'notmuch-show-tags-regexp "(\\([^)]*\\))$")