[Typo3] Errors with standard mail form

[Carsten Gehling]

I've installed typo3 3.8.0 with the "dummy" package. Inside this I've
created a new page with a default "Business" template.

Adding text-content is no sweat. However when I add a standard mail-form to
the page, the following error is displayed on the front-end:

Fatal error: Call to undefined function ctype_digit() in
/usr/local/data/solutions/typo3/typo3_src-3.8.0/typo3/sysext/cms/tslib/class
.tslib_content.php on line 1577

Do I need to install an extension before the mail-form will work?

- Carsten