Whenever I type the word expression into an smail and send it it doesn't appear? Like it just disappears.(even in preview it doesnt show up)

Everything before and after it in the message is still there but the word itself is not?

i've noticed this on pet profiles as well. just fails to show up without affecting any other part of the text. a little annoying when writing stories.

Whoa, that's weird. Perhaps the word "expression" is treated in the PHP coding as declaring an expression in itself? That'd be too weird, though.

If I'm right, it doesn't work on comments on the news articles, as well.

It's been doing this for a looooong time (i.e. years), and I wonder why it hasn't been dealt with yet.

iirc expression is blocked because it's a term that can be used in cookie grabbers.

Yep, pretty sure it and other random works/symbols (like brackets, at least at one point, iirc) are blocked to avoid malicious activities. It sucks, but as a workaround it usually works if you type it with a closed s-code in the middle. Like:

"expression"