Can't send to a Gmail address again

It was working and now it is happening again.  I can't email to a Gmail address.  How do we fix this? 

 host gmail-smtp-in.l.google.com [142.250.102.27]
    SMTP error from remote mail server after end of data:
    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 [secure-lane.com] did not
    550-5.7.26 pass with ip: [66.96.185.10]. 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. vs2-20020a170907138200b00966447ba43asi1145351ejb.517 - gsmtp