At the LRZ mail relays, so-called greylisting is used for spam prevention, among other things. In this process, certain connection data, namely the IP address of the sending mail server and the mail addresses of the sender and the recipient, are stored for 36 days. The period of 36 days was chosen so that emails that are sent, for example, on the first Monday of every month (e.g. newsletters) are not affected by greylisting-related delays. For connections covered by exception lists (e.g. large providers like gmx.de), no connection data is stored. For a description of the greylisting technique, see Spam and virus prevention methods.
Protecting our users and our mail infrastructure from unwanted spam