Mail return code you don't know

Letter of Return code description:
421hl:reptheIPthe sending behavior is abnormal, there is a large number of recipients does not exist, is temporarily forbidden to connect. Please check if any users send virus or spam, and check the validity of the sending list;
421HL:ICCtheIPat the same time, the number of concurrent connections is too large, beyond the limits of NetEase, is temporarily forbidden to connect. Check to see if there are any users who send viruses or spam and reduceIPnumber of concurrent connections;
421HL:IFCtheIPin the short term sent a large number of letters, more than the restrictions of NetEase, was temporarily banned connection. Please check if any users send virus or spam, and reduce the frequency of transmission;
421HL:MEPtheIPAbnormal sending behavior, there is a large number of forged domain domain name behavior, is temporarily forbidden to connect. Please check if a user sends a virus or spam message and sends it using a real and valid domain name;
450mi:celThere are too many error instructions from the sender. Please check the sending procedure;
450MI:DMCthe number of messages sent by the current connection exceeds the limit. Please reduce the number of messages delivered in each connection;
450MI:CCLthe sending party sends more than the normal number of instructions. Please check the sending procedure;
450RP:DRCthe number of recipients sent by the current connection exceeds the limit. Please control the number of messages delivered per connection;
450RP:CCLthe sending party sends more than the normal number of instructions. Please check the sending procedure;
450DT:RBLSendingIPlocated in one or moreRBLin. Please refer tohttp://www.rbls.org/about theRBLrelated information;
450wm:blitheIPnot in the list of sent addresses that NetEase allows;
450wm:bluThis user is not in the list of users allowed by NetEase;
451DT:SPM, please try againmessage body with spam characteristics or sending environment is not normative, is temporarily rejected. Please keep the message queue and re-drop the message after two minutes. Need to adjust the message content or optimize the sending environment;
451Requested Mail action not taken:too much fail authenticationLogon failures are too many and are temporarily disabled. Please check the password and account verification settings;
451rp:celThere are too many error instructions from the sender. Please check the sending procedure;
451MI:DMCthe number of messages sent by the current connection exceeds the limit. Please control the number of messages posted in each connection;
451MI:SFQthe sender thethe number of letters in minutes exceeds the limit, please control the frequency of the sending;
451RP:QRCthe sender's cumulative number of recipients exceeds the limit in the short term, and the originator is temporarily forbidden to send the letter. Please reduce the user's sending frequency;
451Requested Action aborted:local error in processingthe system temporarily fails, please try to send again later;
500error:bad Syntaxusent bySMTPcommand syntax is incorrect;
550mi:nhd HELOthe command is not allowed to be empty;
550MI:IMFThe sender's email address is not compliant . Please refer tohttp://www.rfc-editor.org/definition of e-mail specification;
550MI:SPFSendingIPof the domain that was not sentSPFLicense. Please refer tohttp://www.openspf.org/about theSPFdefinition of the specification;
550MI:DMAthe message was not sent to the sender domain.DMARCLicense. Please refer tohttp://dmarc.org/about theDMARCdefinition of the specification;
550MI:STCThe number of connections for the sender on the day exceeds the limit, and the sender's message is no longer accepted on that day. Please control the number of connections;
550RP:FRLNetEase mailbox Not open anonymous forwarding (Openrelay);
550RP:RCLThe number of recipients exceeds the limit, please reduce the number of recipients per message;
550RP:TRCThe sender's cumulative number of recipients in the day exceeds the limit, and the sender's message is no longer accepted on that day. Please reduce the user's sending frequency;
550DT:SPMmessage body with a lot of spam characteristics or sending environment is lack of normative. Need to adjust the message content or optimize the sending environment;
550 InvaliduserThe requested user does not exist;
550User in blacklistthe user is not allowed to send letters to netease users;
550User suspendedThe requested user is in a disabled or frozen state;
550Requested Mail action not taken:too much recipientthe number of mass exceeds the limit;
552Illegal AttachmentSending attachments of this type is not allowed, including the. uu. pif. scr. Mim. hqx. BHX NaNd. vbs. bat. com. vbe.vb. js. WSHattachments at the end;
552Requested Mail action aborted:exceeded mailsize limitthe size of the letter sent exceeds the maximum limit that the NetEase mailbox is allowed to receive;
553Requested Action not taken:null sender was not alloweddo not allow sender to be empty, please use real sender to send;
553Requested Action not taken:local user only SMTPthe type of machine only allows the sender to be the user of the site;
553Requested action not taken:no SMTP mx only mxtype of machine does not allow the sender is the site users;
553authentication is required SMTPAuthentication required, please check client settings;
554DT:SPMthe message sent contains information that is not licensed or is recognized as spam by the system. Please check if there are any users who send viruses or spam messages;
554dt:sumenvelope sender and letter hair person does not match;
554IP is rejected, SMTP auth error limit exceedtheIPthe connection was temporarily blocked by too many validation failures. Please check the verification information settings;
554hl:ihuSendingIPsuspended because of the sending of spam or the presence of an unusual connection behavior. Please check the letters.IPThe history of the letter and the sending procedure is abnormal;
554HL:IPBtheIPnot in the list of sent addresses that NetEase allows;
554MI:STCthe sender will not accept the sender's investment letter on the day that the accumulated number of messages exceeds the limit. Please reduce the frequency of the sending;
554MI:SPBThis user is not in the list of users allowed by NetEase;
554IP in blacklisttheIPnot in the list of sent addresses that NetEase allows.

This article from the "Erick" blog, declined to reprint!

Mail return code you don't know