fix no space after token in MIME header

src/cpp/Attachment.cpp

@@ -330,8 +330,10 @@ Attachment::readMime (ifstream &mbox, streamoff &curPos) {
       lastVar = line.substr (0, colonPos);
       toLower (lastVar);
       LOG ("find var: " << lastVar);
-      // XXX check in RFC if " " after ": " (=> +2 or +1)
-      string val (cleanString (line.length () >= colonPos+2 ? line.substr (colonPos+2) : ""));
+      ++colonPos;
+      if (line.length () >= colonPos && line [colonPos] == ' ')
+	++colonPos;
+      string val (cleanString (line.length () >= colonPos ? line.substr (colonPos) : ""));
       LOG ("new var: <" << lastVar << " <=> " << val << ">");
       env [lastVar] = val;
     }