TLDR: Yes, a domain can have multiple DKIM records, and most domains that send through more than one service have several. Each service publishes its own record at a unique selector (like google._domainkey.yourdomain.com or s1._domainkey.yourdomain.com ), so they never conflict. Unlike SPF, which allows only one record per domain, DKIM has no limit on how many selectors you can add. The only rule:...