Internet and e-mail policy and practice
including Notes on Internet E-mail


2010
Months
Apr

Click the comments link on any story to see comments or add your own.


Subscribe to this blog


RSS feed


Home :: Email

21 Apr 2010

More on portable email addresses Email

Last month a bill in the Israeli Knesset would have required ISPs to provide portable e-mail addresses, analogous to portable phone numbers that one can take from one phone company to the other. As I noted at the time, e-mail works differently from telephone calls, and portability would be difficult, expensive, and unreliable. So I was wondering, idly, if we really wanted to provide portable e-mail addresses, how hard would it be?

Telephone number portability works by looking up the number in a global shared database before routing each call. The Internet has a global shared database in the DNS, and each time a mail message is sent, the sending system looks up each recipient address in the DNS to see how to route it. But the lookups are just for the domain name, the part after the @ sign, not for the whole address.

If we could adjust the syntax of mail addresses so both the user part and the domain got a DNS lookup, then it would be technically straightforward to port an address from one provider to another. I realized that some mail systems have done this all along. If someone's mail address were bob@example.com we can put the user name into the domain, and make the address something@bob.example.com, where the something is arbitrary. I've offered this option to my users for years, as a way to do tagged addresses, with the new form of the address equivalent to bob-something@example.com at delivery time, something that turns out to take one line of code to implement in the mail system I use.

Several ISPs offer user mail addresses in this form. Panix in New York and Demon Internet in London have done so since the early 1990s, and there are probably others I haven't run into. All of them do this to provide multiple addresses for their users, but with some degree (well, a large degree) of adminsitrative effort, they could arrange their DNS so that specific users' mail is delivered to other mail systems.

If you know in advance that you want to keep your mail address when you switch ISPs, you can register your own domain for $10 - $15/yr, but for people who aren't that adventurous, mail addresses with the user name after the @ sign offer, in principle, portable addresses too.


  posted at: 00:43 :: permanent link to this entry :: 3 comments
Stable link is https://jl.ly/Email/moreport.html

Topics


My other sites

Who is this guy?

Airline ticket info

Taughannock Networks

Other blogs

CAUCE
Remembering JD Falk - 10 years later
385 days ago

A keen grasp of the obvious
Italian Apple Cake
85 days ago

Related sites

Coalition Against Unsolicited Commercial E-mail

Network Abuse Clearinghouse

My Mastodon feed



© 2005-2020 John R. Levine.
CAN SPAM address harvesting notice: the operator of this website will not give, sell, or otherwise transfer addresses maintained by this website to any other party for the purposes of initiating, or enabling others to initiate, electronic mail messages.