看退信下面的日志，并按照相應(yīng)的錯誤信息進(jìn)行匹配。
511 sorry, no mailbox here by that name
unknown user account
... User unknown
Name server reports domain name unknown
mailbox unavailable
550 Invalid User:
invalid recipient
No such user here
All recipients are invalid
User unknown in virtual alias table
Mailbox not found
Recipient address rejected: User unknown in relay recipient table
以上信息均為收件人地址錯誤或者無效，檢查收件人地址，檢查郵件服務(wù)器的域名解析服務(wù)器
554 Connection refused(mx). MAIL FROM [test@test.com] mismatches client IP [74.86.11.12].
域名和IP 地址不對應(yīng)導(dǎo)致的拒收 [上面的域名和IP 地址會變化，類似的情況]，修正您的域名解析，域名解析請參考：http://www.huangjinying.cn/windows/install/954.html
553 5.7.1 SpamTrap=reject mode, dsn=5.7.1, Message blocked by BOX Solutions (www.box-sol.com)
SpamTrap Technology, please contact the MUSTEK site manager for help: (bkndr63272).
如果出現(xiàn)類似上述的信息是因為您發(fā)了不受對方歡迎的信件，導(dǎo)致對方拒收
551 User not local; please try
郵件被GFW 過濾，GFW 是指Great Firewall，中國國家防火墻。嘗試將郵件內(nèi)容打包壓縮或者放入OFFICE 文檔內(nèi)進(jìn)行郵件傳輸
Winsock Error 10053 Connection abort.
網(wǎng)絡(luò)通訊故障
Winsock Error 10060 The connection timed out.
連接超時，網(wǎng)絡(luò)通訊故障造成
Winsock Error 10061 The connection timed out.
對方服務(wù)器拒絕連接，對方服務(wù)器主動斷開鏈接，這通常是由國外不活躍的服務(wù)器造成的。
452 4.3.1 Out of memory
This message is 60 minutes old; it has 0 minutes left in this queue
Remote queue lifetime exceeded; message placed in retry queue
一般情況下，郵件會進(jìn)入重試隊列進(jìn)行再次發(fā)送，這種情況下對方的郵件服務(wù)器一般是Exchange，這是Exchange 的內(nèi)部錯誤造成的。
553 Requested action not taken: no smtp MX
收件人郵箱地址錯誤，域名無法被解析,檢查收件人地址，或者對方域名解析設(shè)置錯誤。
501 syntax.helo hostname
501 Invalid domain name
502 unimplemented command
503 5.0.0 polite people say HELO first
533 relay restriction
544 <>:Recipient address rejected: Relay access denied
傳輸中的語法錯誤，原因不明。
