MD5 challenge issue when setting up email on iOS devices

SmarterMail
To resolve the MD5 challenge issue when setting up email on iOS devices, follow these steps:
  1. Open Settings on your iOS device.
  2. Navigate to Mail > Accounts.
  3. Select the email account that is experiencing the issue.
  4. Tap on Account again within the account settings.
  5. Scroll down and select SMTP under the Outgoing Mail Server section.
  6. Choose the Primary SMTP Server listed.
  7. Find the Authentication setting. If it is set to MD5 Challenge-Response, change it to Password.
  8. After making the changes, tap the back button to return to the previous screen and then tap Done to save the settings.
The MD5 Challenge-Response authentication method can cause problems because it is not universally supported by all email servers. Many servers and applications have moved away from MD5 due to security concerns and compatibility issues. If your server does not support MD5 Challenge-Response, setting the authentication to "Password" should resolve the issue (SmarterTools).

If you continue to experience issues after making these changes, it may be worth checking if there are any additional updates required for your email server or if the email provider needs to make any server-side changes to support different authentication methods(Apple Discussions).

Article ID: 37, , Modified: 9/3/2025 at 10:11 AM

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