Hi,
UTF8 and base64 encoding are the defaults. I have the same setup and the email don't have question marks in the history on my end, even though they also have special characters.
I think that this issue is either:
- you're using an old version of HikaShop where there is a bug on this
- there is a problem with the hikashop_email_history table in your database. Maybe the tables were migrated at some point, or something, and the charset or collation of the table where the emails are stored for the history is not what it should be for some reason.
In any cases, the email history area is usually not used much besides for debugging email issues. So it shouldn't matter that the preview of the emails sent has question marks there. I would just ignore the problem if I were you.