- "Regexp that matches safe url names. Some HTML mails might have a
-trick of spammers using <img> tags. It is likely to be intended to
-verify whether you have read the mail. You can prevent your personal
-informations from leaking by setting this to the regexp which matches
-the safe url names. The value of the variable `w3m-safe-url-regexp'
-will be bound with this value. You may set this value to nil if you
-consider all the urls to be safe."
+ "Regexp matching URLs which are considered to be safe.
+Some HTML mails might contain a nasty trick used by spammers, using
+the <img> tag which is far more evil than the [Click Here!] button.
+It is most likely intended to check whether the ominous spam mail has
+reached your eyes or not, in which case the spammer knows for sure
+that your email address is valid. It is done by embedding an
+identifier string into a URL that you might automatically retrieve
+when displaying the image. The default value is \"\\\\`cid:\" which only
+matches parts embedded to the Multipart/Related type MIME contents and
+Gnus will never connect to the spammer's site arbitrarily. You may
+set this variable to nil if you consider all urls to be safe."