# Contact list domain routing

Contact list domain routing serves two functions in postal route configuration:

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**Grouping**

Logically group domains owned by the same parent company that share a common email infrastructure, such as the merger of Yahoo, AOL, and Verizon. 
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**Isolating**

Routing the most important mailbox providers like Gmail through the API, SMTP Relay, or MTA delivery policy where you're getting the best deliverability\*.
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**\***Delivery is when a message is successfully delivered, Deliverability is when the message hits the inbox.
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Logical grouping example from the portfolio of Yahoo domains:

<figure><img src="https://2024949584-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2FHNgw7cfnOYHQr0B6GDXr%2Fuploads%2Fe3W6Q9bJHJttMuhg9FEQ%2FScreenshot%202023-06-09%20at%209.08.29%20AM.png?alt=media&#x26;token=f3fef5b7-346c-4db1-ba75-5813b72e9cfa" alt=""><figcaption></figcaption></figure>

Microsoft email domains:

<figure><img src="https://2024949584-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2FHNgw7cfnOYHQr0B6GDXr%2Fuploads%2F7fOWA422rteQrhMnXVtN%2FScreenshot%202023-06-09%20at%209.08.47%20AM.png?alt=media&#x26;token=c9b7622c-d36a-4097-9837-38a96d818c73" alt=""><figcaption></figcaption></figure>

Preparing to isolate delivery for Gmail contacts via an optimized postal route connection:

<figure><img src="https://2024949584-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2FHNgw7cfnOYHQr0B6GDXr%2Fuploads%2FQ3MbtD5xJogotg2oWB2b%2FScreenshot%202023-06-09%20at%209.08.18%20AM.png?alt=media&#x26;token=6a01f29a-03b8-4f99-8ae4-c6ede2a76d26" alt=""><figcaption></figcaption></figure>