My customer says nobody can send email to them as of this morning. This has been working fine for 6 months. Now when I sent a test email to them from my gmail account I get this:
Technical details of permanent failure:
PERM_FAILURE: Google tried to deliver your message, but it was rejected by the recipient domain. We recommend contacting the other email provider for further information about the cause of this error. The error that the other server returned was: 550 550 5.7.1 220.127.116.11 has been blocked by BlackList - blackholes.wirehub.net (state 14).