AOL Mail is one of the most popular email providers that serve their users with quick and reliable services. But as with all other email providers, users face issues while using AOL Mail too. For instance, users often face the AOL mail error err604. This error is associated with email delivery.  

• Step 1:An internet connectivity problem might result in the AOL Mail Err604. So, check your internet connection. If you have a poor connection, you will have to fix it at the earliest to avoid further complications.
• Step 2:In case your computer has any antivirus or firewall installed on it, you can disable it temporarily. Once you have disabled it, attempt sending your email again.
• Step 3:Check your account configuration. The outgoing server settings need to be the following:
• Step 4:Outgoing Server: smtp.aol.com
• Step 5:Port Number: 465
• Step 6:Encryption Type: SSL
• Step 7:You can also try removing your account, add your credentials once again, and check if the issue has been resolved.
• Step 8:Try updating the Mail application. For this, you have to check the software updates on your computer. After updating the Mail application, you can try resending the email.

You can also try the following fixes to resolve the AOL mail error err604issue

Restart your System:

• Step 1:Try restarting your system. This action will help in clearing the internal storage, thereby resolving the issue.

Using a Different Browser:

• Step 1:An outdated web browser might also cause the issue. So, you can try accessing your AOL Mail from a different browser. Otherwise, update the existing browser and try sending your email again.

Clear the Cache:

• Step 1:Try clearing your browser cache. This action will delete all the unwanted information. Your browser performance will also improve. After clearing the browser cache, you can try sending your email again.

Disable Pop-up Blocking Software:

• Step 1:Try disabling your pop-up blocking software. This action might help in solving the problem.

Disable Firewall:

• Step 1:You can try turning off the firewall on your system temporarily. However, you have to turn it on immediately once the error is cleared.
• Step 2:One or more of the troubleshooting tips explained above should help in fixing the AOL mail error err604.