How to fix "sender verify fail"?

[PondRicefied]

Please, how not to verify Sender from a specific domain.

---Error---
sender verify fail for <user1@example.com>: response to "RCPT TO:<user1@example.com>" from smtp.example.com [XXX.XXX.XXX.XXX] was: 550 Invalid recipient/sender mailing address
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I want to know exim.conf which uses whitelist of sender.

[amal_ck]

Hi,

You can disable the "Sender Verification Callouts " in WHM --> Exim configuration editor