I just transfer my domain from gandi and i can't send any email. It keeps returning

Your message did not reach some or all of the intended recipients.

Sent: Tue, 28 Nov 2023 08:18:49 +0000
Subject: test

The following recipient(s) could not be reached:

didier.banlock@gmail.com
Error Type: SMTP
Remote server (172.253.62.26) issued an error.
hMailServer sent: .
Remote server replied: 550-5.7.26 This mail has been blocked because the sender is unauthenticated.
550-5.7.26 Gmail requires all senders to authenticate with either SPF or DKIM.