Which channel requires IP warming as a best practice?

Email channels require IP warming as a best practice because they involve sending messages from a new IP address to recipients in a manner that gradually increases volume over time. This process helps establish a positive sender reputation with internet service providers (ISPs) and ensures that emails are delivered successfully to recipients' inboxes rather than being flagged as spam or junk.

By starting with a smaller volume of emails sent to engaged users, marketers can build trust with ISPs, which monitor sender behavior to determine whether an IP should be trusted or flagged. As the IP reputation improves with consistent, positive sending practices, marketers can then increase their email volume. This approach is crucial in maintaining high delivery rates and effective email marketing campaigns.

In contrast, other channels like in-app messages, push notifications, and content cards do not require this warming process as they do not rely on external reputation mechanisms in the same way that email does. They operate differently and typically don't face the same risks of being filtered out or blocked based on sender reputation.