SMTP Email Error 534 5.7.9 – How to Resolve [SOLVED]

SMTP errors are never wanted by businesses and individuals relying on email for communication. One common issue is SMTP Error 534 5.7.9, which can be frustrating if not understood properly.

This error signals an authentication problem. An authentication error generally indicates an error with your login, but the reasons and solutions may differ depending on your email service provider and the configuration of your email system.

What is SMTP Email Error 534 5.7.9?

SMTP Error 534 5.7.9 generally occurs when the email server cannot validate the user’s credentials during the SMTP authentication procedure. It’s seen when sending an email via a third-party client or using an email marketing platform to handle email warmup or outreach campaigns.

Aside from the SMTP error code, similar messages may accompany it:

• Authentication failed: Please log in via your web browser and then try again
• Application-specific password required

Why does SMTP Email Error 534 5.7.9 happen?

1. Two-Factor Authentication (2FA): Many email providers, such as Gmail, enforce 2FA for additional security. If you haven’t set up the proper authentication method, you may encounter this error.
2. Unapproved or invalid third-party apps: Email providers may block third-party apps (like email marketing platforms or warmup tools) unless there is explicit permission or consent. 
3. Password issues: You may be using your regular password for your email account instead of the application-specific password.
4. Less secure apps setting: Providers like Google restrict access to “less secure apps” unless you enable this setting. This can mean problems for email clients or platforms that don’t use the latest security protocols.

How to fix SMTP Email Error 534 5.7.9

1. Make sure that your email address and password are correct

Start by checking if your email address and password are correct. If there’s a typo or error in your login credentials, SMTP Error 534 5.7.9 may occur. Reset your password if needed and test the connection again.

2. Enable Two-Factor Authentication (2FA) or use app-specific passwords

If you’re using Gmail or a similar provider with 2FA enabled, you’ll need to generate an app-specific password so that the email client or third-party tool (like Warmy) will work properly.

For Gmail, go to Google Account Settings > Security > App Passwords, and generate a unique password for the app you’re using. Then, use this password for authentication instead of your regular Gmail password.

3. Allow less secure apps

If you’re using an older email client or app, you may need to enable Less Secure Apps to grant access to the platform. This is more common with Gmail. Simply head over to Google Account Settings > Security > Less secure app access. Setting this up allows SMTP clients to authenticate successfully.

5. Use correct SMTP server settings

Make sure you are using the correct SMTP server settings for your email provider. For example:

• Gmail: SMTP Server: smtp.gmail.com, Port: 465 or 587, SSL/TLS: Yes.
• Outlook: SMTP Server: smtp-mail.outlook.com, Port: 587, SSL/TLS: Yes.

6. Allow access for third-party email tools

If you’re using Warmy or any other third-party service for email warmup or marketing, make sure that you’ve granted the necessary permissions for that service to access your mailbox. For services like Gmail, you may need to go into your Google Account Settings and explicitly allow access to trusted third-party apps.

How Warmy can help prevent SMTP errors

To prevent errors like SMTP Error 534 5.7.9 and ensure a smoother email experience, Warmy can play an important role. Here’s how:

Authentication checks