HTML entity codes in emails instead of actual characters

Hi there. I’m not sure whether this issue relates to the main Grav system or whether it’s specifically related to the Grav Email Plugin (v2.6.1), but messages are being received with certain characters converted to HTML entity codes.

I sent myself an email containing the following lines, and as you can see some of the special characters have been converted to HTML entity codes - ampersand, single quote, double quotes, less than and greater than.

Ampersand &
Single quote '
Double quotes "
Asterisk *
Less than <
Greater than >
Left single quote ‘
Right single quote ’
Left double quotes “
Right double quotes ”
En dash –
Em dash —
Pound sign £
Dollar sign $
Percentage sign %

Does anyone have any idea what I could do to get all symbols to display as symbols and not HTML codes?