Remote host said: 551 not our customer

EQ Admin

EQ Forum Admin
Staff member
Hello,

Did you see the following error in your mail logs :

Remote host said: 551 not our customer


Most likely your mail server is being used to send spam. Check your web sites for scripts that are being abused and smtp relay rules to make sure spammers can not use your server as an smtp relay. Although it possible that someone could have pointed their MX record to the wrong server, if you are seeing a lot of these errors it's most likely that your server is being used to send spam.
 
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