Bad html in letter.content will be written to message_queue.content, which can corrupt the display of members/notices.pl To re-create: 1) Edit a notice which will show up in the message queue. 2) Make sure 'HTML message' is checked. 3) Add <a href="http://example.com>example.com</a> (notice the missing quotes at the end of http://example.com>example.com in the href attribute) 4) Trigger the notice for a given patron 5) Go to the patron's notices tab 6) Trying to expand any of the notices is now broken due to html corruption. This affects users directly, furthermore, simply fixing the letter template isn't enough because the corrupted html stays in message_queue.content. It can only be fixed by updating message_queue.content directly via the database. We should validate html on any page where the 'HTML message' box is checked in tools/letter.pl.
This was just fixed recently (bug 12123) *** This bug has been marked as a duplicate of bug 12123 ***