Shopify verified email DNS records - which is which?

[Jacco-V]

For each Shopify shop, that sends out verified emails, Shopify requires 4 DNS records. These 4 records have the following pattern:

Name	Type	Value
mailerxyz.9cclimbing.com.	CNAME	012345689abc.p123.email.myshopify.com.
xyz._domainkey.9cclimbing.com.	CNAME	dkim1.012345689abc.p123.email.myshopify.com.
xyz2._domainkey.9cclimbing.com.	CNAME	dkim2.012345689abc.p123.email.myshopify.com.
xyz3._domainkey.9cclimbing.com.	CNAME	dkim3.012345689abc.p123.email.myshopify.com.

Question 1:

The last 3 records are, of course, DKIM records. What is the first one?

Question 2:

For a domain that sends out verified emails for multiple Shopify shops, how can I identify which set of records is for which Shopify shops?