Developer Needed to Build Microsoft 365 Email Provisioning Tool Similar to OutEngine

We are looking for an experienced developer to build an internal email infrastructure management tool similar to OutEngine. The tool will be used to automatically provision and manage large numbers of Microsoft 365 email inboxes across multiple domains and tenants. It must also connect the newly created inboxes to Instantly. This is not a basic dashboard project. We need someone who understands Microsoft 365, Microsoft Graph, tenant administration, domain configuration, mailbox provisioning, DNS records, authentication, APIs, and automation at scale. Core Functionality The system should allow us to: Add and manage Microsoft 365 tenants Add domains to the correct tenant Verify domains within Microsoft 365 Create large batches of Microsoft 365 users and email inboxes Automatically assign the correct Microsoft licenses Generate usernames and passwords based on predefined rules Configure mailbox settings where necessary Export and securely store mailbox credentials Automatically connect or import the inboxes into Instantly Organize inboxes by tenant, domain, campaign, status, and creation date Monitor provisioning progress and failures Retry failed provisioning steps Suspend, replace, or remove inboxes View license usage and available capacity per tenant Maintain detailed activity and error logs DNS and Domain Management Ideally, the system should also help automate or manage: Domain verification records MX records SPF records DKIM configuration DMARC records Autodiscover and other required Microsoft records We may use domain registrar APIs or DNS providers such as Cloudflare. Please mention which registrar and DNS APIs you have previously worked with. Instantly Integration Once inboxes are created, the tool should be able to connect them to Instantly through the available API or another reliable integration method. The system should track: Whether an inbox was successfully added to Instantly Warm-up status Sending status Connection errors Disabled or disconnected accounts Which Instantly workspace or campaign an account belongs to Technical Requirements The finished product should be: Reliable at high volume Built with proper error handling and automatic retries Secure, especially when storing passwords, tokens, and tenant credentials Easy to operate without developer assistance Capable of processing thousands of inboxes Designed so that additional providers or features can be added later Fully documented Hosted on our own server or cloud environment Owned completely by us, including all source code The tool should not be a collection of fragile scripts. We need a stable internal platform with a clear dashboard, queue system, logs, and status tracking. Relevant Experience Please apply only if you have strong experience with several of the following: Microsoft Graph API Microsoft 365 administration Azure applications and authentication Microsoft Entra ID Multi-tenant Microsoft environments Automated user and mailbox creation License assignment Domain and DNS automation Instantly API or cold-email infrastructure Queue systems and background workers Secure credential storage Large-scale automation platforms Experience building email provisioning systems, reseller platforms, hosting-control panels, or tools similar to OutEngine is highly preferred. Deliverables We expect: A working web-based dashboard Microsoft tenant and domain management Bulk mailbox creation and license provisioning Instantly integration Secure credential management Logs, retries, and error monitoring Deployment on our infrastructure Complete source code and ownership Technical documentation A reasonable period of testing and bug fixing after launch Application Questions Please include the following in your application: What relevant Microsoft 365 or Microsoft Graph projects have you built? Have you automated mailbox and license provisioning before? Have you worked with multiple Microsoft tenants? Have you integrated with Instantly or a similar cold-email platform? How would you securely store tenant credentials, passwords, and API tokens? What technology stack would you recommend? How would you handle failed provisioning steps and retries? Please provide examples of similar systems you have built. Give an estimated fixed price or development range. Confirm that all code and intellectual property will belong to us. Start your application with the words “Microsoft Provisioning” so we know you have read the complete job description.