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SMTP Email Error 101 - How to Resolve [SOLVED]

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    Despite the rapid evolution, formalized email continues to be one of many cornerstones of contemporary communication, certainly with regard to the professional environment where reliability and clarity are necessary. The Simple Mail Transfer Protocol is a service standard developed in 1982 because of the Internet. This protocol is applied to direct emails through the internet to successfully deliver messages across almost all networks.

    Simply put, SMTP is responsible for the two sending outgoing mail and the means through which servers communicate to make sure that the emails go correctly into the correct email bins. It is vital to have a fundamental understanding of how SMTP operates since it influences the fate of the emails you submit. Mistakes made in SMTP could create failures in your messages, which means they may be slow, delivered late, or not delivered at all. This guide will teach you about SMTP Email Error 101, a common problem that affects many senders.

    SMTP email error 101

    An SMTP Email Error 101 occurs when it fails to connect to the email server, consequently failing to send the email. The error is usually communicated in a notification or an alarm by the email client or application. The message normally rephrases as

    “Connection to server has failed”

    and sometimes

    “SMTP Server Error: 101”. The alarm may also include other messages like “Network is unreachable”


    “Cannot connect to SMTP server”;

    all these phrases indicate that there is a network problem. The error may manifest in different ways due to the client’s behavior or network connectivity state. In a given network environment, the email send failure may be periodic, with emails sending at times and not sending when the error alarms. Alternatively, you might be unable to send the email at all during the downtime.

    Identifying the eauses of SMTP email error 101

    Network Connectivity Issues

    The most common reason of SMTP Error 101 is an issue with the network connection. This might be the result of an unreliable internet connection, network congestion, or temporary disruptions in the network infrastructure.

    Incorrect SMTP Server Settings

    If the SMTP server settings are incorrect—for example, the wrong server address, port number, or security protocol—connection attempts may fail, resulting in Error 101.

    Firewall or Security Software Interference

    Firewalls or security applications on your machine or network may unintentionally prevent connectivity with the SMTP server. Adjusting the settings of these security programs may remedy the problem.

    ISP Restrictions

    Some Internet Service Providers (ISPs) may prohibit connections to specific SMTP servers, especially if they detect spam or other dangerous email activity. This can impede successful email delivery.

    Server Downtime or Overload

    If the SMTP server is offline, undergoing maintenance, or just overwhelmed with requests, it may be unable to receive incoming connections, resulting in Error 101.

    Outdated Email Client

    An obsolete email client may be incompatible with modern SMTP protocols or security requirements, resulting in connection failures.

    Step-by-step fixes for SMTP email error 101

    For Gmail

    1. Check Internet Connection. Ensure your internet connection is stable and strong.
    2. Verify SMTP Settings. Ensure the following SMTP settings are correct:
      • SMTP server: smtp.gmail.com
      • Port: 587 (with TLS) or 465 (with SSL)
      • Require SSL: Yes
      • Require authentication: Yes
      • Username: Your full Gmail address
      • Password: Your Gmail password
    3. Allow Less Secure Apps. If using less secure apps, ensure that you allow them in your Gmail settings (though this is not recommended for security reasons)

    For Outlook

    1. Check Network:.Like with Gmail, ensure your network connection is stable.
    2. SMTP Settings. Confirm the following settings:
      • SMTP server: smtp-mail.outlook.com
      • Port: 587
      • Encryption method: STARTTLS
      • Authentication: Yes (your Outlook email and password)
    3. Update Outlook. Ensure your Outlook application is updated to the latest version.

    For Yahoo

    1. Internet Connectivity. Verify that your internet connection is working without interruptions.
    2. SMTP Configuration:
      • SMTP server: smtp.mail.yahoo.com
      • Port: 465 (SSL) or 587 (TLS)
      • Require SSL/TLS: Yes
      • Authentication required: Yes (your Yahoo email and password)
    3. Check Account Security. Make sure you have not enabled any security features that block third-party email clients.

    General Troubleshooting Steps for Other Email Services

    1. Restart Your Email Client. Sometimes, simply restarting your email client can resolve transient issues.
    2. Disable Firewall/Antivirus. Temporarily disable any firewall or antivirus software that might be blocking your outgoing emails.
    3. Check for Server Downtime. Visit the email service’s official website or third-party status checkers to see if there are any announcements about server maintenance or downtime.
    4. Contact ISP. If none of the above steps work, contact your ISP to see if they are blocking SMTP ports 465 or 587.

    Technical Adjustments

    • Command Line Testing. Advanced users can use command-line tools like telnet or openssl s_client to connect to the SMTP server. This can help verify if the SMTP port is open and accessible from your network.
    • Update Network Drivers. Ensure that your network adapters have the latest drivers installed.

    Choosing ‘System email only’ permits only essential system notifications to be sent, while ‘No access’ halts all outbound emails, providing a safe environment for testing or when email communication needs to be paused temporarily.

    Exploring SMTP error 111

    SMTP Error 111, commonly reported as “Connection refused,” suggests that the email client is unable to establish a connection to the server’s specified port. Unlike Error 101, which generally points to broader connectivity issues, Error 111 specifically indicates that the connection attempt to the SMTP server was actively denied.

    Methods to Resolve SMTP Error 111

    1. Verify Server Details. Double-check the SMTP server name and port settings in your email client. Ensure that there are no typos or incorrect details.

    2. Check Server Status. Verify whether the SMTP server is up and running. You can check the server status through the service provider’s status page or by contacting support. Server downtime or maintenance could be blocking connections.

    3. Inspect Firewall Settings. Ensure that your firewall, either on your local machine or network, is not blocking access to the SMTP server. You may need to configure your firewall to allow outgoing connections to the SMTP port (commonly 25, 587, or 465).

    4. Network Configuration. Check your network’s configuration settings. Ensure that there are no rules or settings that specifically block connections to the SMTP ports.

    5. Consult ISP. Sometimes, ISPs block certain ports used by SMTP servers to prevent spamming. Contact your ISP to confirm if they are blocking the ports and if they can provide a workaround.

    6. Test with Telnet or SSH. Advanced users can use Telnet or an SSH client to manually connect to the SMTP server using the specified port. This test can help confirm if the port is open and listening, and if not, it can indicate where the block might be occurring.

    7. SSL/TLS Settings. If your email setup requires a secure connection, make sure that SSL or TLS settings are correctly configured according to your email provider’s requirements. Incorrect security settings can also cause the server to refuse connections.

    Optimizing email performance with Warmy.io


    Warmy.io provides a set of tools and services aimed at improving email deliverability and reducing typical SMTP issues like Error 101 and Error 111. Warmy.io’s complete approach to email system management may dramatically improve the reliability and efficiency of your email communications.

    Features of Warmy.io

    • Free Email Deliverability Tests. Warmy.io offers tools to test the deliverability of your emails. These tests help determine if your emails are likely to reach the inbox or get filtered out by spam filters, providing insights into potential issues that could be causing SMTP errors.
    • Blacklist Monitoring. Being listed on an email blacklist can severely affect your email deliverability. Warmy.io monitors various blacklists to check if your domain or IP address has been blacklisted and offers solutions to help you get delisted.
    • Free SPF and DMARC Record Generators. Warmy.io provides tools to generate Sender Policy Framework (SPF) and Domain-based Message Authentication, Reporting, and Conformance (DMARC) records. These records are crucial for authenticating your outgoing emails and ensuring they are not rejected by recipient servers.

    Consulting with an Email Deliverability Expert

    Warmy.io also provides access to email deliverability professionals who may give tailored guidance and support. These professionals can help you comprehend complicated issues such as SMTP failures and walk you through the process of adjusting your email settings for best deliverability. If you are having recurring SMTP failures, have deliverability concerns, or need assistance setting up your email authentication records, talking with a professional can give useful insights and practical answers.



    Ultimately, it is essential to minimize the incidences of SMTP errors in order to maintain the integrity and reliability of email communication, an essential part of daily business activities. Errors such as Error 101 and Error 111 disrupt the flow, delay critical messages for minutes, if not hours, and cause loss of opportunity. Awareness of the causes and proper troubleshooting techniques for such errors enable businesses to lessen wasted time and productivity lost to preventable communication issues.

    Email deliverability tools like Warmy.io greatly contribute to improved sender operations. They not only help businesses determine the nature of the SMTP error but also take preventative action to reduce the likelihood of errors from occurring at all. For instance, email deliverability tests, blacklist monitoring, SPF, and DMARC record creation, and other productive activities greatly support the prevention of lost emails and flagged communication.

    📜 Related article:


    Why is email deliverability important in Salesforce?

    In Salesforce, email deliverability is crucial because it directly impacts the effectiveness of your marketing, sales, and customer service efforts. High deliverability rates ensure that your communications reach your audience, fostering better engagement and driving desired actions.

    How can I check my email deliverability in Salesforce?

    Salesforce provides tools to test and measure email deliverability. You can access these tools by navigating to the "Email Deliverability" option under "Setup." Here, you can perform tests and adjust settings to improve your email deliverability rates.

    What are SPF, DKIM, and DMARC, and why are they important?

    SPF (Sender Policy Framework), DKIM (DomainKeys Identified Mail), and DMARC (Domain-based Message Authentication, Reporting, and Conformance) are email authentication protocols that help verify your identity as a sender. They are crucial for building a trustworthy sender reputation, reducing the likelihood of your emails being flagged as spam.

    How do external tools like Warmy enhance Salesforce email deliverability?

    External tools like Warmy complement Salesforce by warming up email domains and improving sender reputation, which are key factors in email deliverability. They offer features like domain warming, analytics, and personalized sending schedules to boost your email performance.

    Can adjusting email deliverability settings in Salesforce impact my email campaigns?

    Yes, adjusting your email deliverability settings in Salesforce can have a significant impact on your email campaigns. Settings like enabling full email deliverability for marketing campaigns or restricting it for testing purposes can help you manage how your emails are sent and received.

    Where can I find more resources on improving email deliverability in Salesforce?

    Salesforce offers a wealth of resources, including documentation, tutorials, and community forums, where you can find tips, best practices, and guidance on improving email deliverability. Additionally, exploring external resources and tools like Warmy can provide further insights and strategies for enhancing your email performance.

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