For a whiff of what is going on, go to the webpresence of Professorette Lann Hornscheidt (it has given itself a "gender-neutral first name):
Do you want to contact Profx. Lann Hornscheidt? Please see that you use a form of address like "Sehr geehrtx Profx. Lann Hornscheidt"."Sehr geehrte(r)" is the formal way addressing a person in a German letter.
Please avoid all two-gendered addresses like "Mr. ___", "Mrs. ___", "Dear (male version)___", or "Dear (female version) ___".
This is no joke. I rather think it's damned frightening. There are 233 chairs for "Gender Studies" at German universities.