·553 refused, SPF check softfail[2016-5-30]
·554 Message not allowed - [299][2016-5-26]
·550 You are blacklisted[2016-5-26]
·421 Sorry, SMTP server too busy right now (90) try again later[2016-5-26]
·550 JunkMail rejected 121.50.xx.xx is in an RBL on rbl.websitewelcome.com[2016-5-26]
·550 The host name specified in HELO does not match IP address[2016-5-26]
·550 5.7.1 Our system has detected that this message is likely unsolicited mail[2016-5-26]
·421 4.7.1 Intrusion prevention active for[2016-5-26]
·554 Rejected due to the sending MTA's poor reputation[2016-5-26]
·553 We have reason to believe this mail is spam[2016-5-26]
·550 5.5.0 121.50.xx.xx is blacklisted by FortiGuard[2016-5-26]
·554 Reject by behaviour spamantispam_bat[2016-5-26]
·550 5.7.1 Client host rejected: Your message was rejected due to spam filtering[2016-5-26]
·550 relaying denied for lightinginfo@yahoo.cn[2016-5-26]
·550 Unrouteable address[2016-5-25]
·543 involves illegal information[2016-5-24]
·553 host denies relay (umail mta)[2016-5-24]
·553 5.1.3 ... Invalid route address[2016-5-24]
·554 refused, spam message[2016-5-24]
·550 RC:NE yao@czrulu.com The email account does not exist[2016-5-23]
·550 5.7.1 Service unavailable, Client host blocked using Spamhaus[2016-5-23]
·550 No RDNS entry for[2016-5-23]
·550 the account is disable[2016-5-23]
·553 sorry, your domain mismatches client IP. Server rejected.[2016-5-23]
·550 Mail rejected[2016-5-22]
·452-4.2.2 The email account that you tried to reach is over quota[2016-5-22]
·550 Remote host is in blacklist[2016-5-21]
·550 5.7.1 Mailbox unavailable. No reverse name (PTR) for your sender IP[2016-5-20]
·554 delivery error: dd This user doesn't have a[2016-5-20]
·550 Mail content denied[2016-5-20]