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SMTP Email Error 422 - How to Resolve [SOLVED]

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    SMTP errors are a significant blow to email communications, causing severe disruption to the smooth flow of this digital necessity for both people and systems. One of these troublesome errors that confront users is SMTP Email Error 422. The most common message when encountering the error is “422 Unprocessable Entity”.

    In general, this SMTP error suggests that the email server could not process the user’s request since the email content or format is not feasible for processing. Thus, an email containing an error with such content cannot be sent and also signals that some configuration or compatibility is breaking the functionality of sending and receiving emails in the user’s environment. Understanding the concept of these errors is vital for getting support in the use of emails.

    Unpacking SMTP email error 422

    SMTP Email Error 422 is mainly known as “422 Unprocessable Entity” and is a type of SMTP Error that occurs when processing email traffic. It means that the server has received the request, and the requested content type is understood, and the syntax of the request entity is correct, but the server was unable to process the contained instructions.

    In other words, the email body, headers, or attachments can be sent in the wrong format from the sending server to the receiving server or there can be several settings provided due to which the email cannot be processed.

    Common causes of SMTP email error 422

    Issues with Message Format

    • Encoding Problems. If the email is encoded in a format that the receiving server cannot interpret or if the encoding declarations are incorrect, the server might reject the message.
    • HTML/CSS Issues. Emails that use complex HTML or CSS may be problematic for servers that are configured to handle only plain text or simple HTML.

    Email Header Errors

    • Incorrect Headers. Headers that are malformed or contain erroneous information can lead to rejections by the email server.
    • Incomplete Headers. Missing critical header information, such as content type or boundary declarations in multipart messages, can prevent the server from processing the email correctly.

    Interested in details? Check out our article – Best Practices for Email Subject Lines and 70 Examples 

    Content That the Server Fails to Process

    • Unsupported Media Types. Attachments or embedded media that aren’t supported by the server can trigger this error.
    • Security Policies. Many servers have strict security policies regarding the types of content they will accept. For example, executable files or links to untrusted sources may be automatically rejected.

    Configuration and Policy Restrictions

    • Anti-Spam Filters. Servers often use sophisticated algorithms to filter out spam. Emails that accidentally trigger these filters due to certain keywords or patterns might be stopped.
    • Size Limits. Emails that exceed the maximum allowed size can also result in a 422 error if the server decides it cannot process such large messages.

    Resolving SMTP email error 422: a step-by-step guide

    For Gmail

    1. Verifying and Adjusting SMTP Settings:

      • Go to the Gmail settings page and select ‘See all settings’.
      • Click on the ‘Accounts and Import’ tab and find the ‘Send mail as’ section.
      • Click on ‘Edit info’ and then ‘Next Step’ to view SMTP settings.
      • Ensure that the SMTP server is set to ‘smtp.gmail.com’, the port is either 587 (with TLS) or 465 (with SSL), and the correct username and password are entered.
    2. Checking the Format of Outgoing Emails:

      • When composing an email, avoid using overly complex HTML or unusual characters that might not be supported.
      • Test sending plain text emails to see if the error persists, which can help isolate the issue to content formatting.

    For Outlook

    1. Correcting Header Information and Ensuring Up-to-Date Configuration:

      • Open Outlook and go to ‘File’ > ‘Info’ > ‘Account Settings’ > ‘Server Settings’.
      • Check the ‘Outgoing mail’ settings to ensure the SMTP settings are correct: typically, smtp-mail.outlook.com with port 587.
      • Ensure that ‘My outgoing (SMTP) server requires authentication’ is checked.
    2. Troubleshooting and Diagnostic Tools:

      • Use the Microsoft Support and Recovery Assistant tool to automatically diagnose and fix issues with your Outlook profile and SMTP settings.
      • If manual configuration is needed, carefully review and adjust the headers by editing the account settings and ensuring all entries are correctly formatted.

    For Yahoo

    1. Reviewing and Modifying SMTP Configurations:

      • Access the ‘Account Info’ page in your Yahoo account.
      • Navigate to ‘Account Security’ and scroll down to ‘Manage app passwords’.
      • Use this feature to generate a unique password if you’re using third-party email clients and ensure SMTP settings are aligned with Yahoo’s requirements: smtp.mail.yahoo.com, port 465 or 587.
    2. Sending Test Emails:

      • Send a few simple test emails to different addresses to see if the issue resolves.
      • If errors persist, reduce the complexity of the email content and try sending again.
      • Document what changes were made when the email was successful to identify what triggered the error.
    warmy dashboard

    Warmy.io provides a suite of tools and services designed to enhance email deliverability and prevent issues like SMTP Email Error 422 from arising. Here’s how you can utilize Warmy.io to improve your email system’s reliability and effectiveness:

    Email Warm-Up Services

    Warmy.io’s email warm-up services are crucial for anyone starting with a new email account or domain. By gradually increasing the volume of sent emails and ensuring they engage positively with recipients, these services help build a robust sender reputation and reduce the likelihood of SMTP errors.

    These services include automated interactions with emails to mimic genuine engagement, which is vital for maintaining good standing with email service providers and avoiding automatic filtering or temporary blocks.

    Free Email Deliverability Test and Record Generators

    Warmy.io offers free tests that analyze your email setup to identify potential deliverability issues. These tests can check for common pitfalls that might lead to SMTP errors, such as incorrect configuration settings or problematic content.

    SPF and DMARC Record Generators. Proper setup of SPF (Sender Policy Framework) and DMARC (Domain-based Message Authentication, Reporting & Conformance) records is crucial for authenticating your email and ensuring it is trusted by receiving servers. Warmy.io provides free tools to generate these records accurately, further bolstering your defense against SMTP errors.

    SPF generator

    Consultation with Email Deliverability Consultants


    For more complex issues or unique setups, consulting with a Warmy.io email deliverability consultant can provide tailored advice and troubleshooting. These experts can offer insights specific to your email infrastructure and help resolve persistent issues related to SMTP errors.


    Taking immediate action to fix SMTP Email Error 422 is critical to maintaining a reliable and efficient form of communication. This error could cause a major disruption in the sending and receiving of emails, thereby affecting personal relationships, communications in business, and even your interactions with clients. Learning the causes and the remedy for SMTP Email Error 422 is important not only in the resolution of the problem at hand but also in future disruptions of a similar nature.

    Various tools such as Warmy.io will assist you in ensuring the deliverability of emails one of the ways in which emails may not meet the technical standards and therefore trigger SMTP errors. Take advantage of their email warm-up services, free deliverability tests, SPF, and DMARC records generator services to maintain and monitor good email health. By doing so, you will reduce disruptions of SMTP Email Error 422 and other similar occurrences. These resources can ensure that your communication will be smooth and timely without any form of hindrance.

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