How Do Agencies Manage Amazon SES Access and Sending for Multiple Clients?

The exact ownership model depends on the contract, but access should generally be handled with IAM roles and trust policies rather than permanent credentials. Infrastructure as code, such as Terraform or CDK, also helps keep identity verification, DNS records, event routing, suppression handling, and monitoring consistent across client accounts.

For larger environments, a centralized mail-management layer can work as an SMTP egress point. It can apply common rules, archive or scan messages, route mail through different SES accounts or external relays, and publish events to centralized monitoring. That approach is useful when clients need shared governance, failover, inbound processing, or detailed operational workflows, but it adds cost and complexity.

The safest default is to keep each client in a separate AWS account and send from there. SES reputation and sending limits are tied to the account and identities, so one client’s poor list quality can hurt deliverability for everyone if you centralize them. Have the client create a cross-account IAM role with a trust policy and external ID. You assume that role when needed, and the client can revoke access immediately without sharing or storing long-lived keys.

The biggest operational headaches are usually getting new accounts approved to leave the SES sandbox, warming up sending reputation, and handling deliverability issues later. Clients often underestimate the importance of SPF, DKIM, DMARC, list hygiene, and aligned sending domains. The infrastructure is fairly repeatable once those processes are documented.