A Simple Guide to Changing Subscriber Domains

In case you haven't heard the news: Wanadoo.nl and Orange.nl were a joint venture between T-Mobile and France Telecom, but that joint venture is now over, and these domains are about to transition back to ownership by France Telecom. As a result, they will stop accepting mail on 1 August. You can read the announcement here (and they even have a FAQ on the transition as well).

What does that mean for people who are sending mail? In this case, not a whole lot. This is a transition that T-Mobile appears to have thought out pretty well. Each user has already been changed to a new email account that ends in @online.nl, and T-Mobile has been changing the subject lines of incoming mail to point out that the recipient needs to tell the sender that to update their address book with the new address since 12 June. Hopefully, that means that your subscribers have already taken care of this (to get rid of the reminder, if nothing else).

But, you want to make certain that things are updated, right? And you would like to know what you should do in the future should some other ISP make changes like this one.

As a rule, when two domains are combined, you will find significant changes to your list for recipients at those domains. Why? Because of name collisions.

And, what are name collisions? Name collisions happen when two people want the same name. They happen all of the time in the "real world". You may, for instance know a couple of people named "Stacy Jones" or "Rick Bell". More broadly, you very likely will know several people with different surnames, but who may be named "Stacy" or "Rick". If your company uses a pattern of firstname@example.com, hiring the second "Stacy" or "Rick" is a problem. The email system (in fact, the entire computer system) depends on every user having a unique identifier (called a "user part"). Where two or more users try to get the same user part brings on a name collision. It's like when two trucks try to occupy the same space at the same time.

When you have two domains that are combining, there is a great probability that you will find many such name collisions. In these instances, it becomes somewhat of a race between users with identical usernames at Domain A and Domain B to get the username at Domain C.

Here's the kicker for people who are sending email then: If they just change the email address from "stacy@domaina.com" to "stacy@domainc.com" they might find that the Stacy from Domain B got it instead, which means that they are now mailing the wrong Stacy.

You deal with this by sending an email to prompt your recipients to update their information. In this case, you would create a list or a group of people whose email addresses end in "wanadoo.nl" or "orange.nl" and then send them an email saying that you'd like to continue communicating with them, but due to the changes at their provider, you need for them to update their contact email address to their new "online.nl" address.

Then, when the transition day finally arrives, you suppress sending mail to the old domains. This isn't really a problem, as those subscribers would never get your email now anyway. They can be safely suppressed with you being secure in the knowledge that there was nothing that you could do to save them.

Any questions? Leave a comment.