SMTP Error Code 553

smtp;553 5.1.2 The recipient address <example@example.com> is not a valid RFC-5321 address. - gsmtp

host xx.yahoodns.net [x.xx.xx.xx] SMTP error from remote mail server after MAIL FROM:<user@example.com> SIZE=2022: 553 5.7.1 [BL21] Connections will not be accepted from x.xx.xx.xx, because the ip is in Spamhaus's list; see http://postmaster.yahoo.com/550-bl23.html

Medium severity

host xx.yahoodns.net [x.xx.xx.xx] SMTP error from remote mail server after MAIL FROM:<user@example.com> SIZE=2022: 553 Mail from x.xx.xx.xx not allowed - 5.7.1 [BL23] Connections not accepted from IP addresses on Spamhaus XBL; see http://postmaster.yahoo.com/errors/550-bl23.html [550]

Medium severity

failed,5.1.1 (bad destination mailbox address),smtp;553 Relaying disallowed,mx.zoho.com

smtp;553 Message filtered. Refer to the Troubleshooting page at http://www.symanteccloud.com/troubleshooting for more information. (#5.7.1)

smtp;553 you are trying to use me [xx.messagelabs.com] as a relay, but I have not been configured to let you [x.xx.xx.xx, example.com] do this. Please visit www.symanteccloud.com/troubleshooting for more details about this error message and instructions to resolve this issue. (#5.7.1)