When should we migrate our mail servers to IPv6?

In “IPv6 and Email: What’s the Hurry?“, Todd Herr from Return Path argues:

As for migration strategies for email, I’m going to throw one out here that may run contrary to popular thinking: perhaps there’s no need for you to migrate your public facing email streams to IPv6 in the next few years. Instead, I propose that you slow down, focus on some other things first, and then worry about migrating.

A small conversation followed on twitter:

I cannot imagine anyone in the email delivery business risking not to be able to deliver email in the dual-stack world that we are entering. Really I am not crying wolf, for yesterday Daniel Karrenberg wrote:

So it looks like a genuine IPv4 network problem while IPv6 was just fine. A whole new level of redundancy!

Imagine having a path that reaches the desired destination and not taking it. Make no mistake, situations like this will start to appear. They will be routing problems, DNS problems and other unforeseen problems in the largest network interoperability experiment ever.

Todd Herr also advices that “First, you are going to have to listen for outbound email connections on IPv6 from your own customers”. I disagree with that also. The first step is to accept IPv6 traffic on all services before creating outgoing IPv6 traffic. This means that ISPs must be able to accept email coming from IPv6 before sending. And yes I know that while the robustness principle was invented for what one accepts and sends within a protocol’s specification (i.e. what one sends and accepts in an SMTP dialog) it also applies here. One cannot have machines ready to send via a medium where no one is listening. First we build the listeners and then the senders.

The time to deploy IPv6 is now: First the routers, then the servers, next the services and last the users. So yes, you do not have to migrate your email infrastructure to IPv6 tomorrow, but spend this year planning (and testing). In a year the migration clock will be ticking.

One thought on “When should we migrate our mail servers to IPv6?

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s