When I email to my list using a SMTP server that I built, I usually encounter this error after a few days:
smtp; 550-5.7.1 [xxx.xxx.xxx.xxx 18] Our system has detected that this message is 550-5.7.1 likely suspicious due to the very low reputation of the sending IP 550-5.7.1 address. To best protect our users from spam, the message has been 550-5.7.1 blocked. Please visit 550 5.7.1 https://support.google.com/mail/answer/188131 for more information. q18si1481423ejf.153 - gsmtp
Anyone can help to deal with this error?
smtp; 550-5.7.1 [xxx.xxx.xxx.xxx 18] Our system has detected that this message is 550-5.7.1 likely suspicious due to the very low reputation of the sending IP 550-5.7.1 address. To best protect our users from spam, the message has been 550-5.7.1 blocked. Please visit 550 5.7.1 https://support.google.com/mail/answer/188131 for more information. q18si1481423ejf.153 - gsmtp
Anyone can help to deal with this error?