Same problem here. Checked on v2.9.1 and v2.8.5. On the first one everything hangs on pressing the submit button. In 2.8.5. it also hangs but the email is sent nevertheless. I checked it on new installation and with plugins with database lg set to once latin II and once to utf8. No change.
If anybody has the same problem or knows how to resolve it just post it here.
