Provider Routing feature gives you complete control over your email sending rules by allowing you to select which ESP (Email Service Provider) sends emails to which recipient ESPs. This advanced option can help improve the deliverability of your sending accounts.
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Access it from the Advanced Campaign Settings. You can:
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1. Choose a sender ESP (e.g., Google) and specify the recipient ESP (e.g., Others) - you need to remove "All" from the dropdown as shown in the video below.

2. Prevent emails from being sent between certain ESPs, such as blocking emails from Other ESPs to Microsoft.

3. Combine multiple rules to create precise email routing strategies for various providers.
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