@Michael Stewart I will try my best to answer your questions below. Please note that this feature just launched in public preview state so items like documentation are currently being written for the General Availability (GA) launch. We traditionally do not recommend implementing preview features into production environments as there may still be key features in developments, bugs, SLAs are often not honored until GA, and support is not provided until GA.
- We currently do not have any specific best practices to share at this time for managing email between hosted domains. We'll take this feedback to our docs team to see if they would consider this feedback.
- Increased Limits: HVE increases the outbound message limit to 100,000 recipients per day during the public preview. Transactional Model: HVE uses a transactional model based on the number of emails sent. Cost: During the public preview, HVE is free but limited to the specified recipient volume. At general availability, the limits will be expanded, and tenant admins will have control over volume thresholds and costs. Recipient Rate Limits: While HVE allows higher volumes, recipient rate limits for all licenses remain at 10,000 recipients per day for both outbound and internal messages. Admin Controls: HVE allows admins to set their own limits on a per-account basis and provides consumption-based billing, usage metrics, and tracking.
- Recipient Limit Enforcement: During the HVE preview period, the 2,000 external recipients per day limit will be enforced by the system. If you exceed this limit, you will receive an error message.
- Same as #1. We do not have public documentation available yet.
- DNS Configuration: To ensure that DNS configuration changes are correctly implemented for Azure Communication Services, it is recommended to follow the guidelines provided in the documentation. You will need to add necessary DNS records for sender verification to succeed
- The domain ownership verification process for Azure Communication Services involves verifying that you own the domain you want to use for sending emails. This can be done by adding a TXT record to your domain's DNS settings.
- To monitor your bulk email usage against the new limits, you can use the Azure portal or Azure Communication Services REST APIs to retrieve usage data.
- Following the blog here for future updates is likely the best place to receive information: https://techcommunity.microsoft.com/t5/exchange-team-blog/public-preview-high-volume-email-for-microsoft-365/ba-p/4102271
- The next large update will likely be announcing the feature as going GA. Typically, there is not much communication between public preview and GA with most products as the team is busy getting the product ready.
- I would take this to a specific M365 forum as I deal mainly with Azure, and this is getting to be outside the scope.
I hope this helps to provide some clarity. Let me know if you have any further questions.