When migrating to SFMC it’s critical that your new sending IP address is appropriately “warmed” to send typical volumes to customers. If you have SAP, your IP address will be brand new with no history to verify that you are a legitimate sender. Without IP warming, email sends can be seen as spam by email service providers or blocked from reaching customers completely.
An IP warming plan starts with sending low volumes of email, and then consistently increasing the send volume over a set period of time. During this time, the ISPs that are sent to will evaluate the behaviour of the sending IP address, as well as the email content and list health to establish your sender reputation.
I developed an IP warming strategy with a goal to send 650,000 newsletters in one day for an automotive client. The original plan was 5 weeks of IP warming, with a grace period of 3 weeks until retirement of their old platform. It turns out we needed those extra 3 weeks; Microsoft issues and a week of no newsletter sends at all extended the plan to 8 weeks. So start early and allow for bumps along the way.
Here are the key takeaways I learnt while IP warming in SFMC.
Parallel campaign deployment
In order to effectively warm a new IP address in SFMC to support full database email sends without
a) compromising its IP reputation and
b) impacting campaign volumes during this phase
send emails from SFMC and the retiring platform at the same time, in parallel over at least 4 weeks. This is because SFMC cannot send to the full volume of subscribers immediately without high risk of damaging the SFMC sending IP.
Target the most active subscribers first
Sending to engaged subscribers who have opened or clicked on a message recently will quickly build up your IP reputation. Segment customers based on engagement, followed by a breakdown of your most popular ISPs. At the start of each IP warming week, provide a send list from SFMC. This will act as exclusions for sends performed in the retiring platform. Over time, shift the ratio of sends from SFMC and the old platform to have the majority sent from SFMC.
Be conservative with Microsoft
We followed Salesforce’s recommended daily ISP limits for IP warming. However, jumping from 40,000 to 80,000 Microsoft sends caused blocked bounces. To recover from this we kept the blocked bounces in an Auto-Suppression List. We gradually re-introduced them over 3 weeks, using SQL to remove them from the Auto-Suppression List and put them back into the pool of customers. Our deliveries and bounces recovered immediately, and remained consistently high/low respectively.
Use send throttling
Along with controlling the volume of emails sent per day, use send throttling to cap the number of emails sent per hour. This will help to establish your IP reputation by gradually sending large volumes over time. Avoid large single sends early on which could trigger spam filters.