Well actually control characters, but I really really like the title. So…
Well, it all started as an escalated issue. My manager asked if I could help with an interesting problem. A user was copying text from Outlook into search bars in different sites, or into the database, and for some reason, the pasted text always contained extra characters.

It took us a while to realize that the extra characters being copied, were actually special characters. We started looking into Outlook itself. We went through all the settings, but couldn’t find anything obvious.
We then spoke with administrators of the website and database; still nothing.
It then occurred to me that we may have gone through all settings thoroughly, so I took another look at the Outlook settings. Under File > Options > Mail > Editor Options > Advanced I found this:

Problem solved!
Interesting to note that this only happened when pasting in certain sites. Other site like Google did not have this problem.