Top Email Senders by Domain | Dataford Interview Questions

Write a query to find the top three most frequent email senders for each customer domain, using window functions.

Use the provided customer domain and email message data. Exclude messages without a sender and return only domains with at least one valid sender.

Output

One row per selected sender and customer domain.
Columns: domain_name, sender_email, message_count, and sender_rank.
Return up to three senders per domain, ordered by domain name, message count descending, then sender email ascending. Break ties alphabetically.

customer_domains

Column	Type	Description
domain_idPK	INT	Unique customer domain identifier
domain_name	VARCHAR(255)	Customer email domain

email_messages

Column	Type	Description
message_idPK	INT	Unique email message identifier
customer_domain_id	INT	Customer domain associated with the message
sender_email	VARCHAR(255)	Email address that sent the message

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