Public Suffix List

Dear HTTP and DNS Operations WGs,

The following email message will shortly be sent to the technical
contact for all TLDs. Yngve Pettersen at Opera suggested that I also let
you both know about it.

The technology in question, including a version of the list, is about to
ship in Firefox 3, but we'd like to verify and improve the quality of
the underlying data.

Please let me know if you see any way I can improve the email, the
explanatory website, or the submission process.


Dear Technical Contact,

The Mozilla Project (, responsible for the
Firefox web browser, requests your help.

We are maintaining a list of all "Public Suffixes". A Public Suffix is a
domain label under which internet users can directly register domains.
Examples of Public Suffixes are ".net", "" and "".
In other words, the list is an encoding of the "structure" of each
top-level domain, so a TLD may contain many Public Suffixes. This
information is used by web browsers for several purposes - for example,
to make sure they have secure cookie-setting policies. For more details,

We would like your help to make sure, now and in the future, that the
entries for your TLD(s) are correct. It is in your interest as a
registry to make sure that this is so. Any errors may either cause your
customers (domain owners in your TLD) to not be able to set cookies when
they should, or cause cookie information to be leaked between two
domains without a trust relationship. Neither of these things is desirable.

Therefore, we are writing to ask your technical team to view the current
list and, if it is incorrect, to submit updated data. A description of
the format of the list, and details for sending updates is at:

We also ask you to send updated information whenever you change your
registration policies in a way which affects the list.

Thanking you in advance,

Gervase Markham

Received on Monday, 9 June 2008 10:01:41 UTC