Codes of successful email delivery
If an email is sent successfully, DirectMail or the recipient server will return a code: “250 send mail ok”, which indicates that the email request operation is completed, and the email has been sent to the recipient server successfully.
If an email is sent successfully, but the recipient does not receive it. The solution is as follows:
Ask the recipient to check whether the email was put into the spam email folder.
Ask the recipient to add your sender address to the whitelist, and then send the email again.
If the email still cannot be received after adding the sender address to the whitelist, ask the recipient to submit this issue to the email service provider for resolution.
Codes of failed email delivery
If an email fails to deliver, the related error codes will be returned. The 4xx return codes are indicative of temporary errors. The 5xx return codes are indicative of permanent errors. If a temporary error is returned by the recipient server (the return code is 4xx), the email will be resent a few times.
Return codes can differ for each email service providers. They represent different reasons why emails fail to deliver.
Common error codes from DirectMail
Error codes from DirectMail refer to the error codes returned during a mailing request to DirectMail, or the return codes returned by DirectMail during delivery.
Type of return code | Return code | Solution |
The X-AliDM Settings value in the configuration item header is incorrect |
| Unknown configuration value error The LinkType value in Unsubscribe is incorrect The Filter Level value in Unsubscribe is incorrect Please refer to the document Configure the Message Header to Control the Specified Function for SMTP Sending Method to view the valid values |
Authentication failed | 535 Authentication failure | Check whether the email sending address or password is correct. |
Number of recipient addresses exceeded | 556 The number of RCPTs is over the size limit | The recipient address limit has been exceeded. The limit for one email please refer to Limits. Reduce the number of recipients. |
Email size exceeded | 557 The length of DATA content has reached the maximum threshold | The email size limit is exceeded. Reduce the size of the email. |
Invalid recipient address | 559 Invalid rcptto | The recipient address is invalid. Check whether the address is correct. |
MX resolution query failed | 423 Dns resolve error 524 Host not found by dns resolve 526 No data by dns resolve | The recipient domain name MX resolution query failed. Ask the recipient to check the resolution (MX) record of the domain name. |
Connection failed | 427 Socks Connect to UNREACHABLE host | The target host cannot be reached. This is typically because the resolution (MX) record of the recipient domain name does not exist. Ask the recipient to check the resolution (MX) record of the domain name. |
Email sending quota exceeded | 552 Monthly sending quota exceeded 552 Daily sending quota exceeded 552 Not enough sending quota | Email sending quota has been exceeded. |
Spam rejection error | 554 Reject by content spam | The email has been tagged as a spam email. Modify the content and send again. |
Abnormal email sender account status | 551 Main account unavailable | The current account is restricted or in an abnormal status. Log on to the DirectMail console to view the current account status. |
Same Domain Authentication |
| The Directmail does not receive mail directly, please do not use the same domain name as the recipient's corporate mailbox as the sending domain name. |
Common error codes from the recipient servers
Error codes from the recipient servers refer to the return codes received from the recipient inbox during delivery.
Note: xx represents any symbol; $EMAIL represents email address; $IP represents email sender IP; $DOMAIN represents domain name.
Type of return code | Return code | Solution |
Recipient address not found | 521 Recipient address rejected 550 5.1.1 https://support.google.com/mail/?p=NoSuchUser 550 5.1.1 https://support.google.com/mail/answer/6596 550 Invalid User 550 Mailbox not found 550 user not exist 550 User not found 554 delivery error: dd Sorry your message to $EMAIL cannot be delivered. This account has been disabled or discontinued 554 delivery error: dd This user doesn’t have a $DOMAIN account ($EMAIL) The email return code includes the following information: account does not exist invalid address invalid mailbox invalid recipient invalid user is not a valid mailbox is not a valid user mailbox not found no mailbox by that name no mailbox here by that name no such address no such mailbox no such recipient no such user recipient does not exist recipient is not exist recipient not found recipient unknown unknown or illegal alias unknown user user not exist user not found user unknown | 1. Please check whether the recipient address entered is correct, such as whether there are extra spaces or special characters. 2. Please check whether the recipient's MX resolution is configured correctly. If there is an invalid MX, please contact the recipient's mailbox administrator for handling. 3. Please contact the recipient through other ways to confirm the use status of the mailbox and whether there are expired, disabled or frozen situations. |
Account blacklist | 550 Mail is rejected by recipients 550 sender in prision 550 User in blacklist | The recipient or the system has blacklisted the sender account. Ask the recipient to check their blacklist and filter policy. If the account is not blacklisted, ask the recipient to submit this issue to their email service provider for resolution. |
IP blacklist | 450 DT:RBL 554 HL:IPB 550 DY-001 550 DY-002 550 OU-001 550 OU-002 550 SC-003 550 SC-004 550 in an RBL 550 ip in prision 550 Your IP address is blacklisted 550 5.7.1 Service unavailable; client [$IP] blocked using $DOMAIN 553 5.7.1 [BLxx] Connections will not be accepted from $IP 554 5.7.1 Client host [$IP] blocked using $DOMAIN 550 5.7.1 Mail from IP $IP was rejected due to listing in Spamhaus SBL 550 IP $IP is blocked 554 IP in blacklist 598 ip address in blacklist The email return code includes the following information: denied by RBL in a DNS blacklist in the RBL is filtered by RBL is listed in RBL 550 Your IP will be reported for abuse - better watch out next time | The email sender IP is blacklisted.Please contact the receiver administrator or service provider for release. |
Recipient address confined | 450 4.2.1 https://support.google.com/mail/answer/6592 550 Mailbox unavailable or access limited | The recipient has received a large number of emails. To avoid malicious attacks, the recipient address is temporarily confined. Wait a moment, and then resend the email to the recipient. |
IP frequency limit exceeded | 421 HL:ICC 421 HL:IFC 421 RP-001 421 RP-002 421 RP-003 550 Connection frequency limited 550 IP frequency limited | The email sender IP frequency limit has been exceeded. Stop sending emails temporarily, and then retry sending the email. If the IP frequency exceeds the daily email sending quota, no email is allowed to be sent on that day. The frequency limit is confidential data belonging to the recipient and is not publicly available. |
Email sending account frequency limit exceeded | 451 MI:SFQ 550 MI:STC 550 RP:TRC 554 MI:STC 550 Sender frequency limited | The email sending account frequency limit has been exceeded. Stop sending emails, decrease the frequency, and resend the email later. If the email sending account frequency exceeds the daily email sending quota, no email is allowed to be sent on that day. The frequency limit is confidential data belonging to the recipient and is not publicly available. |
Email sending domain name frequency limit exceeded | 550 Domain frequency limited | Email sending domain name frequency limit has been exceeded. Stop sending emails, decrease the frequency, and resend the email later. If the email sending domain name frequency exceeds the daily email sending quota, no email is allowed to be sent on that day. The frequency limit is confidential data belonging to the recipient and is not publicly available. |
Spam email | 421 4.7.0 [xx] Message from ($IP) temporarily deferred 421 4.7.0 [xx] Message temporarily deferred 421 4.7.0 https://support.google.com/mail/answer/188131 450 Requested action not taken 451 DT:SPM 550 DT:SPM 550 SC-001 521 5.2.1 : AOL will not accept delivery of this message 550 5.7.1 Message rejected as spam by Content Filtering 550 Mail content denied 550 Suspected spam 554 Message not allowed The email return code includes the following information: as spam is spam spam denied spam detected spam filtering suspected spam contain the spam contents | The emails are suspected to be batch emails, are flagged as spam, or have been complained about by multiple users. Advertisement and promotion emails may only be sent to subscribed recipients. Ask subscribed recipients to add the email sender address to their whitelist. Ask recipients to add the email sender address for registration and notification emails to their whitelist. If the emails still cannot be received after adding the email sender address to their whitelist, ask the recipient to submit this issue to their service provider for support. |
Email size exceeded | 550 Message too large 552 Requested mail action aborted: exceeded mailsize limit | The email size is exceeded. Decrease the email size. |
Full mailbox | 452 4.2.2 https://support.google.com/mail/?p=OverQuotaTemp 452 4.2.2 https://support.google.com/mail/answer/6558 552 5.2.2 https://support.google.com/mail/answer/6558 550 mailbox limit exceeded 552 mailbox is full 552 5.2.1 Quota exceeded or service disabled The email return code includes the following information: is over quota exceed mailbox quota | The recipient’s mailbox is full. Ask the recipient to clean up their mailbox. |
Recipient temporarily unavailable | 400 the mta server of unexpected closed 450 Service temporarily unavailable 451 $DOMAIN Resources temporarily unavailable 451 4.7.1 Sorry, the service is currently unavailable 451 Internal resource temporarily unavailable 451 Resources temporarily not available 451 Temporarily unable to process your email | The recipient system is temporarily unavailable. Resend the email later. If resending failed, ask the recipient to submit this issue to the email service provider for resolution. |
Account greylisting | 450 4.2.0 <$EMAIL>: Recipient address rejected 451 4.7.1 Greylisting in action 451 Grey bounce The email return code includes the following information: grey listed | The email sending account is greylisted by the recipient. Ask the recipient to add the email sender address to the whitelist, and resend later. If resending failed, ask the recipient to submit this issue to the email service provider for resolution. |
Incorrect recipient address format | 501 Bad address syntax 550 MI:IMF | The recipient address format is incorrect. Confirm the correct email address with the recipient. |
SPF validation failed | 520 ip and spf record not match 550 MI:SPF 550 SPF check failed | SPF is set for the email sending domain name, but fails to validate. |
Sender address was reported | 560 Recipient Reported Spam [@ou060102] | The reporter sends an email to aliyundm@alibaba-inc.com asking for lifting the ban and promising not to report the sender address in the future. |
Recipient unsubscribe | 562 Unsubscribed rcptto [@ou060105] | Do not send marketing, subscription, or other types of emails to this recipient. If it is a trigger type email such as a verification code, please use the trigger address type to send such emails. |
SPF, DKIM, DMARC protocols are not properly configured or fail verification | 550 5.7.26https://support.google.com/mail/answer/81126#authenticationbi4-20020a170902bf0400b001d781dc0f70si782764plb.591 - gsmtp | Gmail and other service providers require SPF, DKIM, and DMARC to be configured in domain resolution. For more instructions, please refer to: Gmail Delivery Guidance |
Return codes of some email service providers
Email service provider | Return code description |
QQ Mail | |
NetEase Mail | |
263 Mail | http://www.263.net/263/helpcenter/mailbounce/20150906/842.html |
Gmail Mail | |
Microsoft Mail (such as @hotmail.com, @live.com, @live.cn, and @outlook.com) | |
Mimecast | https://community.mimecast.com/s/article/Mimecast-SMTP-Error-Codes-842605754#451 |