Personalization rules are business logics that you can apply on top of your product recommendations. Personalization rules enable you to tailor the recommended product set to your business needs. You can create a personalization rule by using a base logic. A base logic is nothing more than a product recommendation logic that returns a selection of products based on a pre-defined calculation. Once a base logic has been selected, you can add business-specific criteria that filters your product catalog based on your use case, for example filtering based on price range or including/excluding certain brands or categories.

To check the existing rules, navigate to Content > Personalization Rules.

Personalization rules work only for contacts who have received a campaign (any email communication) in the last 180 days. All other contacts are excluded, they are left out from the personalization rules' target audience. This means that the contact in question will have their email canceled and not sent to them at all. The email could also be canceled if conditions within the rule are too strict, yielding not enough recommendations for the contact.

The prerequisites for using Personalization rules are the following:

• Existing, up-to-date Product catalog
• Implemented Web Extend
• Block-based email campaign including at least one repeatable product block with editable fields: Link, Image, Title, CTA to display a product and it is also repeatable.
• Having either of the following email campaign types: recurring and batch email campaigns.
• Before starting the calculation of a personalization rule, you have to send an email to the target of your campaign. This is needed for the correct synchronization of the contact data before the calculation.  

All the existing Personalization rules that have been created earlier in your account are listed on the Personalization rules page.

For more information, see Defining a Personalization rule.

• Adjusting the delivery speed - When scheduling an excessive number of campaigns within a limited timeframe, we may need to adjust the delivery speed of these campaigns. This ensures our system resources are optimized and can reliably accommodate all our clients requests.
• Staggered scheduling - We strongly recommend staggering your email campaign schedules. Do not time them concurrently to prevent any potential delays in campaign delivery. Employing many personalization rules across simultaneous email campaigns can lead to a threshold breach (approximately 50 personalization rules per email campaign), which may result in slower processing depending on the availability of our backend resources. The primary effect of this on our customers would be a potential slowdown in email delivery times. We are committed to maintaining the highest service standards and appreciate your understanding in helping us achieve this goal.
• Personalization Rules Limitation - The maximum number of Personalization rules per campaign: 5.
• Custom fields - Custom fields can be used within the rule builder with the caveat being that they can only be parsed as strings. This means that only string-based comparison operators can be used on these fields to create Personalization Rules.
• Field Usage Limitation - We suggest using a maximum number of 20 different fields per campaign. This means that if there is 1 field used in 1 rule, and the same field used in the other rule, it means all-in-all 1, and also if it is a localized field it counts as 1, no matter how many language versions they have.
• Multi-language - If you have a localized product catalogue (this is currently a piloting product), you can use the localized fields within Email campaigns in conjunction with Personalization Rules. However, you cannot use localized fields within the rule builder itself when creating a Personalization Rule.
• Calculation wait time - In Product Source Settings, you may see a warning if the calculation is not ready. Email campaigns sent earlier than the personalization rule calculation is finished will result in “no content” errors (the personalization cannot be completed).