You’ve done your research, vetted the solutions, decided on your vendor of choice and signed the contract. Now you have a new marketing automation platform (MAP) or email service provider (ESP) at your disposal. But here comes the difficult part: migrating to your new platform.

Not to scare you, but anyone who’s gone through this once thinks twice before changing vendors. It takes time, effort, and resources to get it done. This is typically work on top of the work needed to keep getting your email messages out on schedule.

Many organizations bring in consultants like me and my team to help. I’m actually going through this process with two clients right now. One is nearing the end of the migration and the other is just getting started, so I thought I’d share a few actionable tips on how to make the transition as smooth as possible.

1. Dedicate a Project Manager

Yes, the vendor will provide an account manager to help you. I’ve worked with great account managers and not-so-great account managers. The bottom line is that either way, you still need to have someone on your team that is ONLY responsible for making the migration happen. Nothing more, nothing less.

Vendor representatives have the best intentions, but they don’t have a deep understanding of your organization’s email program. Also, they don’t know the players. You aren’t their only client, and – as helpful as they are – you need to have someone on your team to run interference and make sure things get done.

2. Assume a Time-Frame of Three Months – or Longer

Many companies underestimate the time it takes to move to a new platform. In my experience with medium- to enterprise-sized companies, it takes a minimum of three months from the contract signing to completion the migration. It often takes longer.

Sometimes, the delay is on the vendor’s side. I’ve rushed to close deals by the month’s end to get a significant discount for a client, only to find out that we have to wait 30 to 45 days to be assigned an account manager. And sometimes it’s on the client side; see the previous note about assigning a dedicated project manager.

3. Create a Migration Plan

Simply put, this is a timeline for moving sends to the new system. There are a number of different ways to organize your migration; here are a few I use:

1. Friendlies First: By speaking to the different groups doing email marketing, you can get a feel for who’s excited about moving to the new system and who’s not. I often ask for volunteers: these “friendlies” tend to be more patient when issues arise – which they will – and more willing to work with you to resolve problems. They take pride in being first on the new system and are okay with being “guinea pigs.” Additionally, they can be some of your biggest cheerleaders when it’s time to start moving over the less enthusiastic users.
2. Simple to Sophisticated: Within most organizations, you have basic one-off email marketing sends and more complex campaigns that leverage automation, dynamic content, segmentation, and other advanced capabilities. I often start with the simpler ones first, and then slowly move into the more sophisticated programs. This gives you some quick wins at the start and allows your team to slowly get up to speed on all the new platform functionality.
3. By Business Unit: You can also take a very straightforward approach and just migrate by business unit. “Business Unit A” first, then “Business Unit B,” and so on. This is certainly a logical approach and there’s nothing wrong with it, but you may lose some efficiencies in setup by doing it this way.

4. Maintain the Integrity of Your Suppression Lists

Suppression lists are required by law under CAN-SPAM, so you must port them over to your new platform. Most organizations will end up sending emails from both the old and the new system for some period of time during the migration. Therefore, it’s important that the master suppression list lives on both systems and that any additions to it be synced between the two. Though not difficult to do in practice, it does take some thought and planning. You’d be surprised how many organizations overlook this, or realize just before the first-send on the new system that this hasn’t been done.

If you have unsubscribe or suppression lists that are specific to email titles, those have to be moved to the new system, as well. While it’s unlikely that the same email title would be sent from both systems for some period, if suppression lists are by division or group with a variety of titles, sends, stand-alone campaigns, as well as triggered campaigns, you will be sending from both the old and new system for a period. If this is the case, you will need to have the suppression lists available and synced on both platforms or on a customer relationship management (CRM) program that both platforms can access.

5. Confirm That Your Integrations Are Complete

Most of my clients are minimally integrating their MAP with their CRM program. Some are also integrating with Google Analytics or another web analytics program, Drupal, or another content management system (CMS) and/or any host of other systems. One sign of a digitally mature company is a high level of integration. When systems are integrated, all your marketing endeavors will benefit – not just your email marketing.

It’s important not only to set up these integrations, but to test them. There’s nothing worse than thinking that a list query is being updated from the CRM system before every send, only to find out months later that it wasn’t and people who opted-in to receive your email messages haven’t been getting them.

Migrating to a new ESP or a new marketing automation platform is unpleasant, but necessary. Taking some time to think through the migration and manage it accordingly can make it as painless as possible. Try this with your next migration and let me know how it goes.

This article written by Jeanne Jennings was first published by ClickZ on September 29, 2015.