8BITMIME in MAIL FROM: Version 1.25.2

Hi, I have been trying to setup zeptomail, however after lots of investigation I can see the MAIL FROM line in the SMTP logs looks like :-

MAIL FROM:example@example.com BODY=8BITMIME SMTPUTF8

The “BODY=8BITMIME SMTPUTF8” at the end is causing the error

”Failed to send a testing email to “example@example.com“ failed to issue MAIL command: 501 Syntax error in MAIL command”

Is there anyway to turn off the 8BITMIME (or smtp extensions)?