Owners of new .capetown top-level domains may have some trouble using e-mail addresses from their new space on the Internet.
This is because a number of online services still check to see that the top-level domain (TLD) portion of an e-mail address (such as .com, .net, or .za) is only a certain number of characters long.
Even well-established, widely used open source Internet software checks for TLD lengths as short as 6 or 7 characters, despite an old Internet Engineering Task Force document, Request for Comments: 1034 (published in 1987) specifying that TLDs could be up to 63 characters long.
One example of a site in South Africa that only validates e-mail addresses which are much shorter than specified in RFC 1034 is the First National Bank (FNB) online banking site.
FNB checks that a TLD is no longer than 7 characters, according to the error message it spits out when you try to use a [email protected] e-mail address.
FNB was asked why it validates e-mail addresses in this way, but the bank did not respond by the time of publication.
Below is another example: a regular expression currently in use by vBulletin to validate e-mail addresses.
The final part of the regular expression states that the TLD must be comprised of between 2 and 6 lower-case (ISO basic Latin) alphabetic characters.
Why 6 character TLDs?
But why limit the length of the TLD in an e-mail address to six characters when RFC 1034 allows for 63 characters?
The answer to that may lie in the Internet Assigned Numbers Authority’s database of top-level domains, where until at least the end of 2013 the longest Latin script domain was 6 characters long.
At the start of 2014 a number of new generic top-level domains (gTLDs) came online, some of which were longer than the 6 character record previously held by .museum and .travel.
South Africa’s dotCities domains are examples of such gTLDs which were approved by the Internet Corporation for Assigned Names and Numbers.
dotJoburg, dotCapeTown, and dotDurban domains became available to the general public on a first-come, first-served basis on 4 November 2014.
Thanks to Tim and morkhans for their assistance on this story.