Is there a simpler way to achieve this style of user messaging?

Question

I have created a messaging system for users, it allows them to send a message to another user. If it is the first time they have spoken then a new conversation is initiated,

Answer 1

Why are you breaking up the data into conversations?

If it were me, I would use one table called 'usermessages' with the following format:

+----+--------+----------+-------------+------------+--------+
| id | userto | userfrom | timecreated | timeviewed | message|
+----+--------+----------+-------------+------------+--------+

A conversation is identified by the combination of the 'userto' and 'userfrom' columns. So, when you want to select all of a conversation:

SELECT * FROM usermessages 
WHERE (userto = :userto OR userto = :userfrom) 
AND (userfrom = :userfrom OR userfrom = :userto) 
ORDER BY timecreated DESC 
LIMIT 10