On Friday, November 17, 2017 12:34:06 PM Gao wrote: > Hi, > > I just built a postfix mail server(mail.mytestmx.com) with PostfixAdmin, > SPF and DKIM.,etc. It works very well. Now I try to use the new built > server as the backup mail server of another server (zeta.othermx.com), > so I add a backup domain in PostfixAdmin and setup DNS accordingly. > Later there is an email came with destination to b...@othermx.com, the > relay attempt got rejected at zeta.othermx.com because of SPF. > > So what is the solution here? Should I add the mail.mytestmx.com to > zeta.othermx.com's SPF record and make it trust it? If so are there any > risk?
SPF checks can only be accurately done at the border of your mail receiving architecture. In the case of mail relayed through your backup MX, the backup MX is the boundary and the receipt of mail from the backup MX at the primary is (at least architecturally) internal. White list your backup MX from SPF checks. Depending on what software you are using for SPF checking, exactly how you do that will vary. Scott K
