Mail Policy for the University of Rostock’s central mailing system

The ITMC of the University of Rostock recognizes a massive increase of undesired emails (spam) over the last years. At the moment, much more than 90% of all emails to the domain are undesired.

The University of Rostock has set up an anti-spam filter for the central mail system, which is able to refuse or filter out spams. The blocking and filtering can be switched and off in per user here.


Mail Policy

1. General measures

As a standard, mails are only accepted by the central mail system if they fulfil the following conditions:

  • The receiver email address exists.
  • The sender address of an authenticated transmitted email must correspond with the email address of the registration user ID to avoid a faking of sender addresses.
  • Sender adresses of anonymous emails must not include mail addresses of the central mail system of the University of Rostock to reduce the faking of email addresses.
  • The mail domain of the sender address must have a valid DNS entry. The IP address of the delivering mail client must have a valid DNS entry (Type A-, CNAME or MX-entry and corresponding PTR entry) and must not establish more than 20 connections at the same time.
  • The HELO/EHLO domain of the delivering mail client must not correspond with the receiver address domain and must be transmitted correctly.
  • The spam probability value (SCL value) must be lower than 8. 

2. Tarpitting

For all errors that are created within the SMTP communication by the delivering mail client (wrong SMTP verb, wrong receiver etc.), the next reaction of the mail server will be delayed for 5 seconds (tarpitting).

3. Greylisting

For all mail domains with mail addresses unknown to the University of Rostock’s mail server (hosted domains of external institutions), greylisting is activated.

4. Virus scanner

Every accepted email is checked for viruses. In case of virus contamination, it is cleaned and delivered to the receiver.

5. Spam blocker

The spam blocker is activated as standard. All emails with a spam probability value (SCL value) 8 or 9 are rejected. Every user has the opportunity to adapt this via the Webinterface of the mail server of the University of Rostock for his/her mailbox.

6. Spam filter

The spam filter is switched in as standard. Every user has the opportunity to adapt this via the Webinterface of the University of Rostock’s mail server.

7. Sending of email attachments

The maximum size of attachments amounts to 100 MB. The regular sending of attachments to several receivers per email is not recommended. The sending of annexes is not recommended with a resolution larger than 300 DPI.



Heike Frisch
Tel.: +49 (0) 381 498 - 5322