This is the domain of:

Services

(not-so-complete list) Mails origination from this domain always have a DKIM-header signed using the private key that works for this public key:
MIGfMA0GCSqGSIb3DQEBAQUAA4GNADCBiQKBgQDhYbsKA86s+xkw7XVubJWefhy8cHXogSYukkTeydtsbe+miB6INGlVkj8h8vY17hWc+jsySLRlABSRjQz4WmwNnNWmQCyE3ueL51n7wF11d7RT1jZh39u8TJjtFFToxJcguRkZvkuEYe+sLNNTfjrEoP6yiW9T3JB1K2VdafEKdwIDAQAB
If you happen to receive a mail that doesn't work with that public key, please let us know. The primary mailserver is infra.lukas-martini.de [176.9.249.87], others are allowed as according to the SPF entry:
v=spf1 ip4:176.9.249.80/28 mx:prauscher.ohai.su -all