Updates to High Volume Email (HVE) Public Preview

Faber77 Thank you for sharing additional details! Let me start with your second question: If you have configured SPF and DMARC / DKIM accordingly for your tenant, then yes this applies to HVE as well. 
On your first question: I'd like to understand your migration needs further - I'll reach out to you through private message, so we can discuss your specific case in detail there. 

ThomasOeser thank you for your question! I understand that the pricing model is an important factor in choosing the right solution for you! HVE will have a pay-as-you-go model similarly to Azure Communication Services (ACS) for email. Currently we are still in the process of finalizing pricing and will be able to share more information soon!

Charles_Delautre thank you for your question! The message size limit for HVE is 10 MB, which includes all content - headers, text, attachments & metadata. If you notice that messages below this limit do not go through, please report an issue so we can investigate further!