Look like the zoho mail server is currently blocked by free.fr ISP.
Reporting-MTA: dns; mx.zohomail.eu
Arrival-Date: Tue, 8 Feb 2022 17:23:32 +0100
Original-Recipient: rfc822; *****@free.fr
Final-Recipient: rfc822; *****@free.fr
Status: 451
Action: failed
Last-Attempt-Date: 8 Feb 2022 17:09:13 GMT
Diagnostic-Code: too many errors from your ip (31.186.226.226), please visit http://postmaster.free.fr/
IP 31.186.226.226 is blacklisted for 64818s (too many errors (unexisting recipients, broken connections), testing)