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SMTP Email Error 553 5.7.1- How to Resolve [SOLVED]

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    Smooth email communication is not just expected—it’s essential. Any hitch, like the SMTP Email Error 553 5.7.1, can quickly disrupt the seamless exchange of information, causing delays and frustration. This particular error, a common roadblock in the email sending process, stands in the way of your messages and their destinations.

    Deciphering SMTP email error 553 5.7.1

    SMTP Email Error 553 5.7.1 is a roadblock, indicating your email can’t be delivered, usually due to authentication issues or sender address problems. This error pops up with a message like “Error 553 5.7.1: Sender address rejected: not owned by user,” signaling that the email server has detected a discrepancy in your sending credentials or permissions. The key to moving past this error lies in identifying and correcting these discrepancies, ensuring your emails smoothly reach their intended targets without further interruptions.

    What is SMTP and how does the SMTP server work?

    Root causes behind SMTP email error 553 5.7.1

    Incorrect SMTP Settings

    The most straightforward cause relates to the SMTP server settings, which, if incorrectly configured, can lead to this error. This includes incorrect server names, ports, or security protocols that don’t match the email service provider’s requirements.

    Lack of Authentication

    Email servers require proper authentication to verify the sender’s identity before allowing email dispatch. If the email client isn’t set up to provide this authentication, or if the credentials provided are incorrect, the server may block the email, resulting in Error 553 5.7.1.

    IP Address Restrictions

    Some email servers have strict IP policies to combat spam, only allowing emails from trusted IP addresses. If your IP address is not recognized or has been blacklisted due to suspicious activity, the server may reject your outgoing emails.

    Want to know more? Read also – SMTP Email Error 553- How to Resolve [SOLVED]

    Detailed solutions for SMTP email error 553 5.7.1

    email providers

    Resolving SMTP Email Error 553 5.7.1 involves technical adjustments and a clear understanding of SMTP settings—the configurations that enable your email client to send emails through your email provider’s server. Here’s how you can address this error across different email platforms:

    SMTP Settings Overview

    SMTP settings typically include the server address, port number, and encryption method, which must align with your email provider’s specifications. For example:

    • Server Address. Often looks like smtp.yourprovider.com.
    • Port Number. Commonly 587 for TLS encryption or 465 for SSL.
    • Encryption Method. Specifies how your data is secured, either through SSL (Secure Socket Layer) or TLS (Transport Layer Security).


    1. Adjust SMTP Settings. Ensure your SMTP server is set to smtp.gmail.com, port 587 with TLS, or port 465 for SSL.
    2. Enable Less Secure Apps. In your Google account settings, allow less secure apps to access your account. Note: Consider using App passwords or enabling 2-Step Verification for better security.


    1. Verify Outgoing Server Authentication. Go to your account settings, select the email tab, choose your email account, and click on ‘More Settings’. Under the ‘Outgoing Server’ tab, check ‘My outgoing server (SMTP) requires authentication’.
    2. Adjust SMTP Settings. Set the outgoing mail server (SMTP) to smtp-mail.outlook.com, port number 587, and select TLS as the encryption method.

    Yahoo and Other Platforms

    1. SMTP Settings for Yahoo. Use smtp.mail.yahoo.com as the server, with port 587 and TLS encryption.
    2. For Other Platforms. Consult the provider’s help documentation for the correct SMTP settings. Common adjustments include verifying the server address, port, and encryption method are correctly set.

    General Troubleshooting Steps

    1. Verify Domain and IP Configuration. Ensure your domain’s DNS settings are correctly configured and that your IP address is not blacklisted.
    2. Update Security Protocols. Ensure your email client supports and uses up-to-date security protocols for encryption.
    3. Authentication Details. Double-check that your username (often your email address) and password are correctly entered in the email client settings.

    Leveraging email warm-up services


    Email warm-up services like Warmy.io are essential tools for preventing SMTP Email Error 553 5.7.1 by building a strong sender reputation right from the start. These services gradually increase your email volume and encourage positive engagement, which convinces email servers your account is legitimate, thus reducing the risk of being marked as spam or facing delivery issues.

    Key Benefits:

    • Better Email Deliverability. Warmy.io ensures your emails consistently reach inboxes, avoiding the spam folder.
    • Strong Sender Reputation. A gradual increase in email activity helps establish your account as trustworthy, sidestepping common triggers for SMTP errors.
    • Higher Engagement. With emails that are more likely to be opened, your engagement rates—and by extension, your marketing success—see a significant boost.

    In short, using a service like Warmy.io is a straightforward strategy to enhance your email campaigns’ effectiveness, ensuring your messages are delivered, seen, and acted upon without hitting common SMTP roadblocks.


    Throughout this discussion, we’ve delved into the critical aspects of resolving SMTP Email Error 553 5.7.1 — a prevalent issue that can significantly hinder email communication efficiency. We’ve uncovered the root causes, ranging from incorrect SMTP settings and lack of authentication to IP address restrictions, and provided detailed, platform-specific solutions to address and rectify these issues. Moreover, we’ve highlighted the role of email warm-up services like Warmy.io in building a robust sender reputation, essential for preventing such errors and ensuring seamless email deliverability.

    Addressing SMTP Email Error 553 5.7.1 promptly is not just about fixing an immediate problem; it’s about safeguarding your ability to communicate effectively and maintain vital connections.


    What preventative measures can I take to avoid SMTP Email Error 553 5.7.1?

    Regularly review and update your SMTP settings, ensure proper authentication practices, and monitor your IP reputation to prevent blacklisting.

    Are there long-term solutions for managing SMTP Email Error 553 5.7.1?

    Implementing consistent email hygiene practices, like using email warm-up services and maintaining updated and accurate SMTP configurations, serves as a long-term defense against such errors.

    What role do email service providers play in mitigating SMTP Email Error 553 5.7.1?

    Email service providers can offer valuable support by providing clear guidelines for SMTP settings, offering tools for authentication and reputation management, and assisting with troubleshooting when errors occur.

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