Home » Resolved – AOL Email Error 521 | Causes, Remedies and Preventions

Resolved – AOL Email Error 521 | Causes, Remedies and Preventions

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AOL Email Error 521

AOL being a widely used email service, the users often get error 521 AOL will not accept delivery of this message. What is this error? How does it occur and how you can resolve this AOL email error 521 effectively, we are going to discuss in brief in the further section. So let’s get going!

So, AOL mail is a web based convenient email service for sending and receiving emails for free. While the exchanging of emails is through internet, sometimes there might be issues in the web server like service failure, outages or any other kind of issues. Let’s discuss the whole thing below.

What is AOL Email Error 521

The mail error 521 AOL could occur any legit time. Generally the error has been found out on running a program, simply shutting down or starting up Windows, while sending or receiving emails, or when you are running a program.

Not just that, the question being what is a 521 error in AOL, the error is also seen while exchanging emails in email clients other than AOL. Here is a user query:

I don’t know why am I getting this error message while sending an email from Outlook 2010 to AOL, an error message “521 5.2.1: AOL will not accept delivery of this message” shows up! Please suggest what could be the reason and how do I resolve this AOL error 521 5.2.1?”

Symptoms of AOL SMTP Error 521

Here’s how you detect it is a 521 error:

  • While you are performing program installation, the error 521 could show up.
  • This 521 AOL error can crash your system while you are running the program.
  • If you are starting up or shutting down Windows, AOL error message 521 5.2.1 could show up.
  • The sent / received emails are failed or forwarded to unintended mail servers.

Why Do We Get AOL Email Error 521?

There could be a couple of reasons behind getting this error 521 AOL.

  • The basic reason could be any virus infections on your Windows or AOL program files.
  • Any accidentally or intentionally deleted AOL files.
  • Installation or uninstallation of a recent application could also cause corruption in program files.
  • Incomplete installation or corrupt download of AIM software.

Inevitably, corruption or malicious infections in AOL or Windows program files are the basic reasons of getting the error 521 AOL.

Now, let’s move ahead to know the troubleshoots to AOL email error 521.

Best Remedies to AOL Mail Error 521 5.2.1

Follow up these steps and approaches on how to fix the AOL mail error code 521.


Start with having a recheck on all the Windows registries that are associated with the AOL error 521.

  • Begin a Quick PC Scan: Run a quick scan on your personal computer for viruses or malwares.
  • Start a Disk Clean up: Remove all the temporary files and clean-out the junk with Disk Clean up.
  • Get Your System Drivers Updated: Make sure to update all the system drivers.
  • Move to Windows System Restore: In order to abort all the recent system changes, use Windows system restore.
  • Reinstall your AOL Program: Uninstall and reinstall the AOL software application linked with AOL email error 521.
  • Grab All the Available Windows Updates: Now quickly update your Windows with all available updates.
  • Relax and Restart your System.


As a second approach, you could try this method as well. This technique is applicable if the mail is sent through an email application other than AOL (Recall the above stated user query). For an instance, if the email client is Google Gmail, then make use of the SMTP server of Gmail for the same. All you need to do is configure and enable the TLS security >> insert the login Username with Password and then you will be able to use the SMTP server.

Refer to the Google support: https://support.google.com/a/answer/2520500?hl=en

Also Read: How to Resolve AOL Desktop Error Code 104?

Now the error must be resolved, but what if it is the other way round?

Still No Luck with AOL Error 521?

Hold on! If the error still persists, the last thing you can do is to get in touch with the AOL technical support. They surely will resolve the issue. Here are the contact details of AOL support team ( +1-866-235-1646 ). Take instant assistance and fix the AOL email error 521 or any other AOL issues.

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