Dear Enrico, it seems that your domain hasn't any SPF entry in DNS.
dig txt cerm.unifi.it Fighting spammers is hard, so at least SPF have to be used to legitimate your IPs. DKIM and DMARC are other ways...somewhat more complex to implement. Regards, Paolo. > On 1 Feb 2019, at 15:41, Enrico Morelli <more...@cerm.unifi.it> wrote: > > Dear all, > > I having some problem forwarding some emails to Gmail addresses. > Sometime the emails are bounced cause: > > This message does not have authentication information or fails to pass > 550-5.7.1 authentication checks. To best protect our users from spam, > the 550-5.7.1 message has been blocked. Please visit 550-5.7.1 > https://support.google.com/mail/answer/81126#authentication for more > 550 5.7.1 information. k11si3359248wrp.39 - gsmtp (in reply to end of > DATA command)) > > I'm sure that these emails aren't spam. > > Someone can explain me why? Is there some misconfiguration in my mail > server? > > Thanks > > -- > ----------------------------------------------------------- > Enrico Morelli > System Administrator | Programmer | Web Developer > > CERM - Polo Scientifico > via Sacconi, 6 - 50019 Sesto Fiorentino (FI) - ITALY > ------------------------------------------------------------ ------------------------------------------------------------------------------------------------ Paolo Barbato Consorzio RFX <https://www.igi.cnr.it/>corso Stati Uniti,4 35127 Padova - Italy Network Administrator phone: +39 049 8295097 fax: +39 049 8700718 ------------------------------------------------------------------------------------------------
