You haven't really told us what the problem is. What kind of multiline capability do you need?

I'm guessing since you mention 'can grow' it's about the size of the text boxes for long and short messages?

Access is great for storing and manipulating data. Everything else, not so much.

I personally would use the web browser control (or write an hta (depends on security; you might have issues accessing the database from the browser)). Knowing how to write html/css is very handy and your outputs/reports will look much better and be far more flexible than anything Access can manage.