[Typo3] spamProtectEmailAddresses 404 not found

[Robert Markula]

I'm using spamProtectEmailAddresses in my TS setup:
# Enabling Spam protection for e-mail addresses
config {
   spamProtectEmailAddresses = 2
   spamProtectEmailAddresses_atSubst = (at)
}

But when I click on a E-Mail address in the FE, a 404 "Not found"-Page 
appears:

Not Found
The requested URL /my_typo3_dir/mailto$jr9webmaster at domain.tld was not 
found on this server.

I have realURL and qcom_htmlcleaner enabled.

Greets,
Ro