Knowledge Base/E-Mail Support Forum
Troubleshoot Bounce Backs/NDR E-mail Errors
Carl Gren
posted this on July 27, 2011 11:02 am
Brief Overview of Bounced Back & NDR E-Mail Issues
When you send an e-mail, you might receive a “Bounced Back” or NDR message indicating that the mail was not delivered. Similarly, someone might complaint to you that they had sent an e-mail to you which bounced back to them.
In such cases, there will be a bounce back message which would have been sent to the sender of the e-mail. The bounce back will have certain details.
Technically speaking, when you send an email to some email address and the recipient's email address is closed or not working, you receive an undeliverable email (bounced email). There are two types of undeliverable emails. One is called a soft bounce. Soft bounce happens when there is a temporary error at recipient email address (e.g. the recipient's email server is down for 1 hour). The other type of undeliverable email falls into the category of a hard bounce. This happens when the recipient email address is no longer functioning (closed).
In most cases bounce backs are in non-technical language and you will be able to understand it. The bounce back will also have error codes which can go a long way in understanding the reason for bounce back.
Brief Explanation of Email Addresses
Any e-mail address consists of two sections. The username part and the domain name part. The username is the part in front of the “@” sign and the domain name is the part after the “@” sign.
The email address you are sending to is referred to as the recipient, the person sending the email is the sender.
Common Errors and Suggested Actions
Below is the list of most common errors and reasons for bounce backs & NDR issues.
- If you continue to have problems sending an email and would like us to investigate further, then you will need to send us the complete bounce back message with the headers.
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If you are having problems receiving an email from a particular sender, you should inform the sender of the problem and advise them to contact their e-mail provider first to request additional support. Technology2Reality can and will assist with inbound/receiving problems to the best of our ability, but responsibility for investigating and correcting most inbound email issues will reside with the sending mail server, provider or administrator.
The below given examples do not have headers. However, when you send us a bounce back you should provide us the headers too.
| Error Code | Comments | If You Are Sending | If You Are Receiving |
| 4.3.1 | Not enough disk space on the delivery server. Microsoft say this NDR maybe reported as out-of-memory error. | This indicates that the recipient’s e-mail box is full. | If somebody informs you about this error then your mailbox is reaching its limit. You need to either upgrade your space or archive your old e-mails or delete them. |
| 4.3.2 | Classic temporary problem, the Administrator has frozen the queue. | If you have sent an e-mail and you got this bounce back then the issue is with the receiving server and not with your domain's server. | Not Applicable for us. We do freeze the queue. |
| 4.4.1 | Intermittent network connection. The server has not yet responded. Classic temporary problem. If it persists, you will also a 5.4.x status code error. | This would not happen with Technology2Reality hosting systems or servers. However, if such a situation occurs, then there might be a network issue with the receiving server at the time when our server tried to deliver the e-mail. If this is followed by 5.4.x then please contact our support department with the full header of the e-mail for indepth analysis. If the issue is from our side we will try and fix the issue. | If somebody informs you that they are getting this error then the sending server might be having some connectivity issues. Have the sender try again and if it fails then we need the complete headers of the bounceback message. |
| 4.4.6 | Too many hops. Most likely, the message is looping. | Please check if there is a loop formed with the e-mail address. If somebody sent an e-mail to you and has complained to you that you they got the following bounceback then you need to login into your control panel and verify if there is a loop created for the receiving e-mail address at any point. The issue is not from the server side but the way recipients e-mail address has been set. | If you get this error while sending an e-mail to someone; then you need to let that person know about this. The e-mail address on the other server is not setup correctly. In either case, the issue is not with the sending server or receiving server. It’s the way e-mail address has been setup. |
| 4.4.9 | A DNS problem. Check your smart host setting on the SMTP connector. For example, check correct SMTP format. Also, use square brackets in the IP address [64.xxx.xxx.xxx] You can get this same NDR error if you have been deleting routing groups. | This error will not happen while sending e-mails from Technology2Reality hosting systems or servers. | If somebody complaints to you that they got this error while sending e-mail to you; please have the sender contact his administrator as the SmartHost has not been setup in the right manner. |
| 4.6.5 | Multi-language situation. Your server does not have the correct language code page installed. | Not Applicable to Technology2Reality hosting systems or servers. | Not Applicable to Technology2Reality hosting systems or servers. |
| 5.1.x | Problem with email address. | ||
| 5.1.0 | Often seen with contacts. Check the recipient address. | If you get this bounce back; then please send the complete header to our Support Department. | If you get this bounce back; then please send the complete header to our Support Department. |
| 5.1.1 | Another problem with the recipient address. Possibly the user was moved to another server in Active Directory. Maybe an Outlook client replied to a message while offline. | You might get this error when an e-mail was added to the system and then removed and re-added. Please type the complete e-mail address rather than selecting the user from GAL or drop down. If you don’t receive a bounce back after you have typed the complete e-mail address then you need delete the e-mail address that you get from the drop down and also download the Offline Address Book again | You might get this error when an e-mail was added to the system and then removed and re-added. Please type the complete e-mail address rather than selecting the user from OAB or drop down. If you don’t receive a bounce back after you have typed the complete e-mail address then you need delete the e-mail address that you get from the drop down and also download the Offline Address Book again |
| 5.1.3 | Another problem with contacts. Address field maybe empty. Check the address information. | Not Applicable to Technology2Reality hosting systems or servers. | Not Applicable to Technology2Reality hosting systems or servers. |
| 5.1.4 | Two objects have the same address, which confuses the categorizer. | This is a problem with the receiving server and not with Technology2Reality hosting systems or servers. | Not Applicable to Technology2Reality hosting systems or servers. |
| 5.1.5 | Destination mailbox address invalid. | You have typed an invaild address. There is a typo in the e-mail address or the e-mail address has been deleted. Please verify that there are no typos in the e-mail address or the e-mail address exists. | The sender typed the wrong e-mail address; had a type in the e-mail address or the e-mail address was deleted. Please have the user verify the details. |
| 5.2.1 | The message is too large. Else it could be a permissions problem. Check the recipient’s mailbox. | The mailbox is designed to receive e-mail upto a certain size. Mail sent by you is bigger that the allowed size. If you are sending an attachment then please try and zip the attachment and try to resend it. You may try alternate methods like yousendit.com for sending e-mails of larger size | If somebody is sending you an e-mail which is bigger that 70 MB then they will receive this bounce back. Please have the sender use an alternate method such as yousendit.com. The user can also try to reduce the file size by zipping the file. |
| 5.2.2 | Sadly, the recipient has exceeded their mailbox limit. | This indicates that the recipient’s e-mail box is full. | If somebody informs you about this error then your mailbox is reaching its limit. You need to either upgrade your space or archive your old e-mails or delete them. |
| 5.2.3 | Recipient cannot receive messages this big. Server or connector limit exceeded. | The mailbox is designed to receive e-mail upto a certain size. Mail sent by you is bigger that the allowed size. If you are sending an attachment then please try and zip the attachment and try to resend it. You may try alternate methods like yousendit.com for sending e-mails of larger size | If somebody is sending you an e-mail which is bigger that 70 MB then they will receive this bounce back. Please have the sender use an alternate method such as yousendit.com. The user can also try to reduce the file size by zipping the file. |
| 5.3.0 | Problem with MTA, maybe someone has been editing the registry to disable the MTA / Store driver. | If you get this bounce back then you need to contact the provider. This is not an issue from our side | Not Applicable to Technology2Reality hosting systems or servers. |
| 5.3.1 | Mail system full. Possibly a Standard edition of Exchange reached the 16 GB limit. | This is a problem with the receiving server and not with Technology2Reality hosting systems or servers. | Not Applicable to Technology2Reality hosting systems or servers. |
| 5.3.2 | System not accepting network messages. Look outside Exchange for a connectivity problem. | This is a problem with the receiving server and not with Technology2Reality hosting systems or servers. | Not Applicable to Technology2Reality hosting systems or servers. |
| 5.3.3 | Remote server has insufficient disk space to hold email. Check SMTP log. | This is a problem with the receiving server and not with Technology2Reality hosting systems or servers. | Not Applicable to Technology2Reality hosting systems or servers. |
| 5.3.5 | Multiple Virtual Servers are using the same IP address and port. See Microsoft TechNet article: 321721 Sharing SMTP. Email probably looping. | This is a problem with the receiving server and not with Technology2Reality hosting systems or servers. | Not Applicable to Technology2Reality hosting systems or servers. |
| 5.4.0 | DNS Problem. Check the Smart host, or check your DNS. It means that there is no DNS server that can resolve this email address. Could be Virtual Server SMTP address. | You should not be getting this error when sending e-mails. If you get this error then please contact our Support Department with Complete Headers. | If you receive this error while receiving e-mails then please contact our support by getting the complete bounce back from the sender. |
| 5.4.1 | No answer from host. Not Exchange’s fault check connections. | The issue is with the receiving server. Most cases, either mail services are down or server is down | This may indicate an issue with your Exchange Server. In most cases, either mail services are down for maintenance or other reason. Contact our Support Department for additional information or assistance. |
| 5.4.2 | Bad connection. | Please try sending an e-mail from some other mail service like gmail/yahoo and see if you get the same error. If yes, then the issue is with receiving server and not Technology2Reality hosting systems or servers. | Not Applicable to Technology2Reality hosting systems or servers. |
| 5.4.3 | Routing server failure. No available route. | Please try sending an e-mail from some other mail service like gmail/yahoo and see if you get the same error. If yes, then the issue is with receiving server and not us. | Please contact our support team with the complete headers of the error message. The error usually is with the sending server as it’s not able to route mails. |
| 5.4.7 | Delivery time-out. Message is taking too long to be delivered. | Please try to send an e-mail from some location like gmail/yahoo to isolate the cause. If the problem does not exist when sending e-mail from Yahoo/GmailContact our support department with full headers of the error for additional details | Please try to send an e-mail from some location like gmail/yahoo to isolate the cause. If the problem does not exist when sending e-mail from Yahoo/Gmail. Contact our support department with full headers of the error for additional details |
| 5.4.8 | Microsoft advise, check your recipient policy. SMTP address should be cp.com. NOT server.cp.com. | This error is again for the receiving server and not Technology2Reality hosting systems or servers. | This error will not happen with out servers. |
| 5.5.0 | Underlying SMTP 500 error. Our server tried ehlo, the recipient’s server did not understand and returned a 550 or 500 error. Set up SMTP logging. | This issue happens when our server tries to connect and deliver the mail to the recipient’s server. Try sending e-mail from different providers like gmail/yahoo. If you don’t get a similar bounce back then contact our support department with full headers. | Please have the sender resend you an e-mail from Gmail/Yahoo. If the issue does not come with Gmail/Yahoo, then the sender needs to contact his provider |
| 5.5.2 | Possibly the disk holding the operating system is full. Or could be a syntax error if you are executing SMTP from a telnet shell. | This error would not occur with Technology2Reality hosting systems and servers. This is always on the receiving server's end. | This error will not happen with out servers. |
| 5.5.3 | More than 100 recipients. Check the Global Settings, Message Delivery properties. | You can send to 100 recipients at a time. | Sender needs to contact his administrator and verify the limit. |
| 5.5.5 | Wrong protocol version. | Not Applicable to Technology2Reality hosting systems or servers. | Not Applicable to Technology2Reality hosting systems or servers. |
| 5.6.3 | More than allowed number of attachments. | Please reduce the number of attachments and then try to send e-mail. You may want to zip the files. | The sender needs to contact his provider and verify the limits. |
| 5.7.1 | Permissions problem. For some reason the sender is not allowed to email this account. Perhaps an anonymous user is trying to send mail to a distribution list. | You are trying to send an e-mail to a distribution group outside your company/domain and the receiving group is not configured to receive e-mails from you. Contact the recipient company administrator and they can make the changes. The issue is not with our server/service | If a sender complaints to you that they are trying to send an e-mail to your distribution group/list and they are getting this bounce back, you need to login into your control panel, click on distribution group and uncheck the option “Receive e-mails from same domain/authorized senders” |
| 5.7.3 | Check external IP address of ISA server. Make sure it matches the SMTP publishing rule. | This error is from the server to which you are trying to send an e-mail. You need to contact the administrator of the server. | Not Applicable to Technology2Reality hosting systems or servers. |
| 5.7.4 | Extra security features not supported. Check delivery server settings. | If you get this error, please contact support with full bounce back error message | Sender needs to contact his administrator and verify the settings. |
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