As spammers are quite frequently changing the host part of their sender address we now make use of the possibility to reject mail based only on the user part of the sender address. In this list we find some of the larger Internet providers whose addresses are often forged by spammers. This list is updated once per day. Note that, for technical reasons, these domains also appear in the list of banned domains . Automatic forwarding from within CERN is not affected.
Spammers often use bogus message identifiers to hide their identity.
Attempts to use CERN as a relay are rejected Any mail for which neither the sender address nor the recipient address is registered in the CERN name servers is rejected. If you are outside CERN you must change this to the SMTP server of your Internet provider or the lab where you are physically. If you try to send mail from a machine that is not correctly registered in the CERN central name servers it will be rejected.