PB avec GMAIL Undelivered Mail Returned to Sender

E-mails
1

Bonjour,
Tous les mails que j'envoie sur un id @gmail reviennent avec le message Undelivered Mail Returned to Sender
Que faire?
: host gmail-smtp-in.l.google.com[64.233.184.26] said:
550-5.7.26 This mail is unauthenticated, which poses a security risk to the
550-5.7.26 sender and Gmail users, and has been blocked. The sender must
550-5.7.26 authenticate with at least one of SPF or DKIM. For this message,
550-5.7.26 DKIM checks did not pass and SPF check for [c2c.paris] did not
pass 550-5.7.26 with ip: [51.210.91.29]. The sender should visit 550-5.7.26
https://support.google.com/mail/answer/81126#authentication for 550 5.7.26
instructions on setting up authentication.
u8-20020adfed48000000b0030aebdb909asi391365wro.502 - gsmtp (in reply to end
of DATA command)

2

Bonjour,

Normal, vous n'avez pas de SPF, vous devez le mettre en place.

Cordialement, janus57