Using GAE mail service to send mails.while sending mail to one of ours. I have issue like as below.
Technical details of permanent 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 rejected content, black listed XXXXXX.appspot.com by dbl.dnsbl. #762 #895 (o7F1ZY023821731400) (state 17).
so we look out spamhaus URL : http://www.spamhaus.org/dbl/removal/record/appspot.com In that url
DBL record for appspot.com The domain name appspot.com is listed on the Spamhaus DBL.
appspot.com has been listed in the DBL because it is a spammer abused URL shortener or redirector.
If you are an authoritative administrator of appspot.com and you have solved the abuse issues you can write to us at dbl-mmxi@spamhaus.org from either abuse@appspot.com or postmaster@appspot.com and inform us of the actions you have taken to clean up the current spammer URLs. Please also inform us of any steps you have taken to prevent future abuse of your shortener/redirector. We will review your request and, at our discretion, remove the listing or respond to your request.
Please help to resolve this issue.