Freron MailMate

I'm trying to incorporate command line email client into my workflow. I'm using program called isync/mbsync to sync email from server to my local computer in maildir format.
When I load maildir folders into my command line email client, I noticed that my email address and name did not show correctly in the "Sent" folder. My name contains non ASCII characters that have accents, so "From" header usually has this "MyÁcentěd Name firstnamelastname@email.com".

But when I look directly into raw message it has value that is something like this: "=?utf-8?b?[somelettersandnumbers]=?=" <firstnamelastname@email.com> (I replaced contents of the string with []).

I reached out to isync developers and they assured me that they do not modify contents of the message when syncing them. I then downloaded raw email message from my email provider via their web interface and even there, the "From" field contained the same value.

I started looking into this until I realize that this value in "From" header comes only from Mailmate and not from other email clients.

I'm not sure if that is something Mailmate must do in order to do, it's true that I never heard from other people complaining about my emails looking weird. However it's a bummer as I'd like to use more email clients. Also it's on the server now so not sure if I can do anything about it.

Could you please give me advice? Thanks.