My customer tries to send mails via the Graph API with the result of different looking mails (e.g. font family etc.). After an investigation we found out that the mails are sending each time with a different html encoding.
This seems an issue which is already known and also faced by other people
- https://stackoverflow.com/questions/68319987/how-to-force-emails-delivered-through-microsoft-graph-api-to-use-utf-8-encoding
- https://github.com/microsoftgraph/msgraph-sdk-java/issues/779#issuecomment-849652150
So for our solution it would be every beneficial to set the html encoding for mail body when sending the mail via Graph API.