While working with Exchange Server, administrators always expect its smooth functioning. But out of some unrequired and undesired events like incorrect server settings, logical issues, storage issues, insufficient system resources, etc., the access to Exchange Server database gets hindered. Some Exchange Server errors are frequently encountered, and some are noticed at times. Exchange Server errors with event IDs 451, 452, and 471 are going to be discussed in detail (symptoms, nature, causes of errors) in this blog along with associated solutions to each error code.

To know about these Exchange Server errors, let us have a brief understanding of what causes these errors and what happens when they are encountered.

Exchange Server Errors Event ID – 451 Event ID – 452 Event ID – 471
Causes Comes with the installation of Edge Transport Role in Exchange, due to a misconfiguration in system or address blocked (manually) by recipient domain user Due to Insufficient System Resources in External Server during a connection attempt via SMTP. When error codes – 510, 1024 are generated with 471 event ID, caused due to permission issues, space problems, etc.
Symptoms Exchange users cannot send Emails to any specific domain Transport service stops the submission of emails and delivers the message in the queue that makes them inaccessible at the time Database engine could not roll back operation on the database as specified in this event description. No database entry can be updated now.

Resolving Exchange Server Error 451

To resolve the error “451 4.4.0 DNS Query Failed” displayed in Queue Viewer in Exchange, users can perform reconfiguration process or use TELNET to examine Edge transport layer working for outbound or inbound exchange of email messages.

  1. The first thing you should do for fixing this error is to check Firewall and confirm transport at port 53 for DNS resolution and port 25 for SMTP.
  2. Then inspect Queue Viewer by opening Exchange Management Console on Edge Transport Server. Now locate mail flow tools and select queue viewer tool.
  3. Confirm DNS Configuration – To verify the DNS configuration in Exchange Server, follow the simple steps.
    1. Initially, log in to Edge Transport Server locally and use Console Switch if using the Remote Desktop connection.
    2. Open Exchange Management Console>click Edge Transport Server>select Properties.
    3. Go to Internal DNS lookups, check if it has default configuration settings. If not, set it to the default settings.
  4. Performing Internal and External Lookups –
    • Internal Lookups: For multiple network adapters, users need to access Internal Network Card and select it to access card DNS setting. In the settings, you can modify all IP addresses (if not according to the required configuration).There could be a condition that there is no IP address which means NIC card is not configured with DNS server entries. To compensate for this, fill the NIC card with correct details and confirm them.
    • External Lookups: If you modify the configuration in public DNS setting for users having a single network card, it may affect external name resolution, and thus email flow might get restricted. To correct this, choose to Use this DNS option and select IP of internal DNS. Then, add host file consisting of DNS information. Finally, confirm the configuration once again.
  5. Checking SMTP connection using the TELNET command
    1. Open Command Prompt by typing cmd in Windows+R. In Command Prompt, type telnet.
    2. Type set logfile (location:/filename)
    3. Now, type open mail.abc.com 25 and execute it.
    4. Now, execute the command – EHLO contoso.com.
    5. Compose a test email with email parameters like From, receive, notify, data and subject, etc.

The process terminates with a report displaying success or failure confirmation.

Resolving Exchange Server Error 452

When the insufficient resources become s sufficient enough, the submission of mails, which was stopped earlier, gets back to normal. This resuming process is called Backpressure. To avoid this situation, Exchange Server disk space should be increased to more than 4GB space.

You can resolve this error in few steps. Just follow the sequence one by one.

  1. Take a backup for your Exchange database. Remove the unrequired data from the disk to have some 500 MB free space in your memory.
  2. Disable Backup Pressure through the steps given below:
    1. Using the path C:\Program Files\Microsoft\Exchange Server\Bin, locate EdgeTransport.exe.config
    2. Open this .exe with notepad and locate the add key=”EnableResourceMonitoring” value=”true”. In place of “true”, enter value – “false” and save the file.
    3. Now, start Exchange Transport services again.
  3. Relocating database queue –
    Next step is changing the location or moving the queue of the database to another location. To perform this, consider the steps.

    1. Once again, open EdgeTransport.exe.config with Notepad.
    2. At the bottom, add the code – add key=”QueueDatabasePath” value=”C:\Queue\QueueDB”. Click Save to save this file.
    3. Now, restart Exchange Transport services to view the difference.

This method will help you to resolve the Exchange Error 452 and getting the mail flow clear.

Resolving Exchange Server Error 471

This error must be resolved in order to enable updates in the database. Otherwise, Exchange Server is unable to roll back operation and make future updates on the database. Let us find the solution for the most common error codes for the event 471 – Error 510 and Error 1022.

The main reasons for the Error 510 is spaces issues, permission issues, SAN issues causing the problem to disk reading and writing. The error 1022 occurs when disk I/O restricts Exchange to access a requested page in the database or to a check file. With disk failure due to this error, the complete access is denied for the user.

Solution for Error 510 – To resolve the error, simply troubleshoot the permissions issues, space issues, and other issues that are causing problems to the disk making it inaccessible. Once the actual reasons are found out, solve the issues by providing default or required permissions, eliminating space, and other issues.

Solution for Error 1022 – First of all, just check if the drive in which Exchange store files are stored is accessible or not. If found accessible, run the command chkdsk/f/r. If it does not fix the error, try another way. In this, check for the permissions on the Exchange folder structure. Even then, if the database is unable to mount, check for any file-level antivirus software running on Exchange Server.

Some other issues Exchange admins face

Apart from settings-related error issues, Exchange administrators may face corruption issues too. But good thing is that there are many Exchange Recovery tools to recover data from EDB files. Exchange users can directly access the lost or deleted Exchange data using Exchange Recovery tool. The software converts any type of EDB files to PST format or directly saves them to Exchange too. This third-party software ensures quick, complete and exact EDB recovery.

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Final Words

Exchange administrators may face a lot of issues in the Exchange environment. They can be errors like Exchange error 451, 452, and 471 or EDB file corruption. Exchange errors 451, 452, and 471 can be solved in different ways without any external tools. But to recover data from corrupted or damaged or inaccessible EDB files instantly and flexibly, Exchange administrators should always rely on professional Exchange data recovery tools like Exchange Server.