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Time to Drive Solo? Or Stick With the Carpool?

July 17, 2009 by Chris Wheeler

Repost of my article over at the EEC blog explaining the pros and cons of going with a dedicated IP versus a pool of IPs and impact on email deliverability.

If you have ever dealt with onboarding at an ESP, you probably know
one of the main topics of discussion around scalability and reputation
is whether to go with dedicated or shared (pooled) IPs. Are you ready
to “drive solo” with a dedicated IP, or do you stick with the
“carpool,” an IP pool. It can be daunting and sometimes a bit
ambiguous as to which model fits your needs best. With that in mind,
here are the top 5 factors you need to keep in mind when determining
which path to go down.

1. How much mail are you planning to send?
The
way email is relayed from sender to receiver is fundamentally based on
the IPs (or network fingerprints) involved in the handoff. The more
IPs you have, the more inroads you can create with getting mail
delivered to an ISP (such as Yahoo!, Gmail, etc.). Many ISPs have hard
requirements around how many messages will be allowed through and how
many active IPs you can use at one time. If you’re looking at sending
more than 20,000 per week, you should see if having your own IPs to
send through will give you the scalability needed to match that.
However, if you’re not going to be sending at least that much, you
might have more horsepower than you need which is where a pooled group
of IPs helps – it spreads the load like peanut butter over the
different IPs from the grouped senders.

2. What is the deliverability impact?
Email
deliverability, at least right now, is heavily weighted on IP
reputation. What does this mean? Like a credit report, ISPs will
determine what sort of mail they can expect from an IP based on the
history of mail that’s been coming from it. If you have mail that is
strong enough reputation wise, which includes low bounce rates and end
recipient complaints, a dedicated IP might work. You will only have to
worry about your own mail’s impact as opposed to allowing the
possibility of other mail going out the same IPs impacting your
delivery. But, proceed at your own risk – when using a dedicated IP,
you determine your own fate. Pooled IP senders usually rise and fall
with each other depending on the sum total of mail being sent out where
one particular sender won’t necessarily sway the pool as a whole. This
is why choosing an ESP that has good deliverability rates on a pool is
of paramount importance – you’ll be judged by your peers. A bad
reputation will cost you in the long run.

3. How is dedicated v. pooled different in implementation?
Typically,
a new IP will be warmed up (or pulled from an already warm pool) and
allocated to a sender on a dedicated system. This means special
attention should be given to initial sending and ISP feedback.
Dedicated IPs also require a bit of inflight tweaking as the ISPs learn
what sort of mail will be delivered. But, once this initial ramping
has completed, you’re free to do as you like as long as you don’t
violate any ESP best practices. You also have more wiggle room for
making your IP specific to you since you’re the only one it’s
representing. Pooled IPs generally don’t require much technical
implementation since the sending IPs are ready to go and have a
critical mass of mail already being sent out. However, the business
investment with vetting and passing certain ESP requirements can be
heavy since the new sender has to prove they won’t do anything to risk
the pool’s reputation and thus the existing senders using it.

4. Does the cost make sense?
Dedicated
IPs require more time, effort and maintenance to get everything setup.
They use their own bandwidth which subsequently means the cost isn’t
shared. Most ESPs charge for this as a result. Pooled IPs? There’s
usually no cost associated above and beyond the normal sending
charges. This means money saved for smaller sender.

5. How much autonomy do I want?
This
is a critical question for anyone sending email. Do you care if your
messages go out with custom or group headers? Do you want to be able
to send on your own schedule whenever you want (again, as long as you
stay within the ESP’s published best practices)? How about not having
to worry about what other senders in the same pool are doing? With
dedicated IPs, you get to be in control of a lot more of the decisions
around how email is actually delivered. Many clients don’t care,
though, as email is just a component of a much larger marketing
strategy and as such, they don’t have the resources or capitol to
afford dedicated IPs. In a pool, you’re more heavily scrutinized
depending on any hiccups along the way impacting the greater good.

There’s
a tendency for email marketers to see the issue as black or white
wherein they fall into one or the other side with strong convictions.
It’s not that simple and as email becomes more widely adopted as a
marketing and end customer communication vehicle, taking into account
the above points will help you achieve success no matter where you land.