551 5.7.0 Recipient Domain Does Not Exist In Dns
Eberardo Topher
After office365 hybrid configuration with exchagne2010 i am getting this message Your message couldn't be delivered. The Domain Name System (DNS) reported that the recipient's domain does not exist. Remote Server returned '550 5.4.310 DNS domain does not exist [Message=InfoDomainNonexistent] [LastAttemptedServerName=svr-ex-caht01] [prod.protection.outlook.com]'. This problem only for incoming from external doamin , internal incoming and outgoing fine , and external outgoing fine . 2nd question I just wan to understand why saying domain not exist , user not exist I can understand
It's frustrating when you get an error after sending an email message. This article describes what you can do if you see error codes 550 5.1.1 through 5.1.20 in a non-delivery report (also known as an NDR, bounce message, delivery status notification, or DSN).
You might have an invalid entry in your Auto-Complete list (also known as the nickname cache) for the recipient. For example, the recipient might have been moved from an on-premises Exchange organization to Exchange Online, or vice-versa. Although the recipient's email address is the same, other internal identifiers for the recipient might have changed, thus breaking your cached entry for the recipient.
Does the recipient's email address in your original message exactly match the recipient's email address in the NDR? Compare the recipient's email address in the NDR with the recipient's email address in the message in your Sent Items folder.
If the addresses don't match, contact the recipient (by phone, in person, etc.) and ask them if they've configured an email rule that forwards incoming email messages from you to another destination. Their rule could have tried to send a copy of your message to a bad email address. If the recipient has such a rule, they'll need to correct the destination email address or remove the rule in order to prevent 5.1.x message delivery errors.
Check your recent messages in the Sent Items folder for strange or unknown messages (messages that you didn't send). If you find any, it's possible that your email account was compromised.
Reset your password and scan your devices for malware. However, the hacker might have configured other settings on your mailbox (for example, created Inbox rules to auto-forward email messages or added additional mailbox delegates). So, follow the additional steps in How to determine whether your account has been compromised.
If your Sent folder contains only messages that you know you sent, then the NDR you received could be a result of backscatter (a useless NDR about a message you didn't send), and you can ignore it.
Typically, if a message can't be delivered, the recipient's email system will use the sender's email address in the From field to notify the sender in an NDR like this one. But what if the message was sent by a spammer who falsified the From address so it appears the message came from your email address? The resulting NDR that you'll receive is useless because it creates the false impression that you did something wrong. This type of useless NDR is called backscatter. It's annoying, but if this NDR is backscatter, your account hasn't been compromised.
Check your recent messages in the Sent Items folder for strange or unknown messages (messages that you didn't send). If you don't see any suspicious messages, it's likely that the NDR you received is backscatter. If you've already changed your password and run an anti-malware scan, you can ignore these backscatter NDRs.
If the steps in the previous section don't solve the issue for the sender, the solution might be related to the way the user's Microsoft 365 or Office 365 account is set up. If you have a hybrid topology, the solution might also be related to the on-premises mail transfer agent. It might also be a problem with the recipient's domain configuration. Here are four solutions you can try. You might not need to try all of them to get the message sent successfully.
For Microsoft 365 or Office 365 accounts, the Microsoft 365 admin center provides a central source for various tools, notifications, and information that you can use to troubleshoot this and other issues.
If there's a problem with the recipient's domain, contact the recipient or the recipient's email administrator to let them know about the problem. They'll have to resolve the issue in order to prevent NDR 5.1.x errors.
Error code 5.1.1 can be caused by problems with the MX resource record for the recipient's domain. For example, the MX record might point to an old email server, or the MX record might be ambiguous due to a recent configuration change.
Test your MX record and your ability to send email from your Exchange Online organization by using the Verify MX Record and Outbound Connector Test at Office 365 > Mail Flow Configuration in the Microsoft Remote Connectivity Analyzer.
Problems sending and receiving email messages can be frustrating. If you get a non-delivery report (NDR), also called a bounce message, for error code 550 5.1.10, this article can help you fix the problem and get your message sent.
A spammer sent a message to a non-existent recipient, and they falsified the From address so it appears the message was sent by your email address. The resulting bounce message that you get is called backscatter, and you can safely ignore or delete the bounce message.
Backscatter itself is harmless, but if you're getting much of it, it's possible that your computer or device is infected with spam-sending malware. Consider running an anti-malware scan. Additionally, to help prevent spammers from impersonating you or others in your organization, ask your email admin to read this topic: Set up SPF to help prevent spoofing.
If your original message had an attachment larger than 10 MB, the Send Again option might not be available or might not work. Instead, resend the message from your Sent Items folder. For more information, see Resend an email message.
If your original message had an attachment larger than 10 MB, the Send Again option might not be available or might not work. Instead, resend the message from your Sent Items folder.
Microsoft 365 and Office 365 support multiple ways to forward messages automatically. If the intended recipient of your message is using Microsoft 365 or Office 365, ask them to review the Update, disable, or remove Inbox Rules forwarding and Disable account forwarding sections below.
If the sender can't fix the issue themselves, the problem might be that an email system on the receiving side isn't configured correctly. If you're the email admin for the recipient, try one or more of the following fixes and then ask the sender to resend the message.
In the Active users > Filters search field, type part of the recipient's name, and then press Enter to locate the recipient. If the recipient doesn't exist, then you must create a new mailbox or contact for this user. (For more information, see Add users individually or in bulk.) If the recipient does exist, make sure the recipient's username matches the email address the sender used.
If the user's mailbox is hosted in Exchange Online, click the user's record to review their details and verify that they've been assigned a valid license for email (for example, an Office 365 Enterprise E5 license).
The recipient might have an Inbox rule that is forwarding messages to a problematic email address. Inbox rules are available only to the user (or someone with delegated access to their account). See Update, disable, or remove Inbox Rules forwarding for how the user, or their delegate, can change or remove a broken forwarding Inbox rule.
In the Active users > Filters search field, type part of the recipient's name and then press Enter to locate the recipient. Click the user's record to view its details.
Message routing (especially in hybrid configurations) can be complex. Even if changing the accepted domain setting fixes the bounce message problem, it might not be right solution for you. In some cases, changing the accepted domain type might cause other unanticipated problems. Review Manage accepted domains in Exchange Online and then proceed with caution.
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