Instead, scrlttr2 issues the following warning:
Class scrlttr2 Warning: Usage of package `parskip' together
(scrlttr2) with a KOMA-Script class is not recommended.
(scrlttr2) I'd suggest to use option
(scrlttr2) `parskip' with one of it's several values.
(scrlttr2) Nevertheless, using requested
(scrlttr2) package `parskip' on input line 16.