Merge records with the same email in the EXCEL file when setting up Gmail sending. Send different content only once to the same email address. How should this be done?

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Merge records with the same email in the EXCEL file when setting up Gmail sending. Send different content only once to the same email address. How should this be done?
A A1 [email protected]
B B1 [email protected]
C C1 [email protected]
Merge the data from A, B, and C and send it only once to [email protected]. How should I set this up?