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SMTP Test Tool – FAQ

This is the FAQ for the SMTP Test Tool.

Q: What’s going on here?

A: This is a web-based SMTP test tool. If you’re familiar with SMTP servers and how they work, you know that you can manually telnet into the SMTP server and issue commands like HELO and MAIL-FROM and RCPT-TO to send a test email or just see how the SMTP server responds to commands. This web-based tool makes it so you can run diagnostic sessions on SMTP servers over the web, rather than having to use telnet and issue manual commands, which can be cumbersome.

Q: Why would I need to use this?

A: If you’re having difficulty getting emails delivered by your SMTP server, it might not be readily apparent what the issue is, and you might find yourself writing test code to figure it out. With this tool, you can easily see what’s going wrong with an SMTP server. Perhaps your login credentials are failing. Perhaps the SMTP server has run out of disk space. Perhaps the SMTP account is throttling you because of pre-established sending limits. By looking at the exact SMTP server responses, you can easily troubleshoot an issue.

Q: How is this SMTP Test Tool related to GMass? If I’m a GMass user, do I need to test my SMTP server here?

A: This SMTP Test Tool was created by GMass, and can be used by GMass users, but it’s really for everyone, including non-GMass users. If you’re a GMass user and you’re using the unlimited email sending option by connecting your account to an SMTP server, and you’ve having difficulty connecting your SMTP account, this tool will help you troubleshoot. Even if you’re not a GMass user but are using an SMTP server and having difficulty, this tool will help you troubleshoot.

Q: I’ve found other SMTP testing tools on the web. What makes this one so special?

A: I believe I’ve created the world’s best web-based SMTP testing tool, because with my tool, you can:

  • Authenticate by IP or Username/Password.
  • Specify a port other than 25.
  • Choose from multiple security options, including SSL, TLS, and STARTTLS.
  • See the SMTP conversation happen live before your eyes, shown in an easy-to-read color-coded format.
Q: I’m specifying a Username and Password, but I noticed that in the SMTP session, the Username and Password look a lot different from how I’m entering them.

A: That’s because we base-64 encode your Username and Password before passing it into the SMTP server for validation. That’s part of the SMTP standard.

Q: The SMTP server I’m testing  authenticates by IP address instead of Username/Password. How can I run a diagnostics session?

A: Leave the Username/Password fields blank, and set your SMTP server to accept connections from this IP address: That is the IP address used for outbound connections to the SMTP server that you specify.

Q: If I enter my SMTP Username and Password, is it safe?

A: Yes, it’s pretty safe. We don’t store any of the information entered to test an SMTP server. It simply passes through ephemerally to conduct the SMTP connection test, and then the information disappears from our server.

Q: What happens if my test is successful?

A: A successful test will result in a one-line email message being sent from the email address specified to the email address specified. To protect against this tool being used to send spam, the “test message” cannot be modified.

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  1. I’m getting error:
    ERROR: A call to SSPI failed, see inner exception. I think thats why emails aint going out.

    Anyone how to fix this?

        1. Hi Mohammed,

          You would need to create an SMTP account with an SMTP service provider to utilize sending via an SMTP.

  2. What Username and Password to be used ……

    What is SMTP Server to be used

    Error- ERROR: A connection attempt failed because the connected party did not properly respond after a period of time, or established connection failed because connected host has failed to respond

  3. O suporte deveria ser mais claro no preenchimento do teste.
    Que usuário e senha é esse?
    O email remetente é sempre do gmail?
    Qual site colocar? se não tiver site?
    já fiz de tudo, só dá erro.

  4. The test says please wait. How long as it has been 30 minutes and I am still waiting to do a test. If the test doesn’t work how will the mass?

  5. Please help with the below: My campaign is Stuck

    Campaign-level Error Description:
    Unable to connect to the SMTP server set for your account, mail.XXXXXXXXXXXX.XX. No connection could be made because the target machine actively refused it

  6. Require a little help. This is the error I get after inputting my info to set up the SMTP.

    Your GMass request failed. Error details:
    No connection could be made because the target machine actively refused it Try the SMTP Test Tool to troubleshoot the issue.

    SMTP Server: smtp.sendgrid.net
    Ports: 25
    Username: apikey

  7. Hi GMass,
    Thanks for the SMTP test tool.
    Please consider adding an actual message to be sent along as the message body. It can be as simple as “This is a test message.” It seems according to the SMTP RFC, a completely blank message body is not allowed and some servers honor this requirement strictly (https://tools.ietf.org/html/rfc2045#section-5.1)

    Thank you.

    1. Hello Again,

      i am kee getting errors, SMTP failed. how can use GMass.co SMTP for my email hosting! i did cancel my subscription with Sendgrid.

  8. Hi and thank you for the help.
    I would like to use the smtp function to send 500 to 1k email messages. I am a member of Sendgrid. I’ve tried to use the SMTP tool for some to to no success. I’ve used api then the api id for password. No luck. Tried using my sendgrid user/password no success. Results always invalid username/password. No matter what password I use, either api key; A27UU64MQOuvUhj1lB9ZaQ or the encrypted dots. Login:

    Anyhelp is greatly appreciated.

    1. Hi Bob,

      I’ve edited your comment for your SendGrid account’s security. Please contact our support team at https://www.gmass.co/blog/how-to-get-support-from-the-gmass-team/ so we can assist you directly.

  9. Hello team,

    i got error while sending email in my application is,
    535 5.7.0 Authentication disabled due to threshold limitation

    the mail id i am using is :[email protected]

    Please solve this issue as soon as possible.

    1. Please contact our support team at https://www.gmass.co/blog/how-to-get-support-from-the-gmass-team/

    1. Please contact our support team at https://www.gmass.co/blog/how-to-get-support-from-the-gmass-team/

  10. according to your article on how to set sendgrid smtp with your smtp in gmail. in place of username do i input: apikey and password as the api key i generated? or what i’m i supposed to enter in those fields?

    1. Hi Augustine,

      Yes that’s correct if using the API key generated in your SendGrid account, you’ll need to use the username apikey with the password being the actual API key generated.

  11. I keep getting this error message

    successful sends 450
    general exception unable to connect to smtp server
    it is disconnected please help

  12. getting this error
    > Date: Wed, 02 Oct 2019 14:29:03 퍍
    >> Subject: SMTP test from email-smtp.eu-west-1.amazonaws.com
    >> Message-Id:
    >> To: [email protected]
    >> MIME-Version: 1.0
    >> Content-Type: text/Test message
    >> .
    <> RSET
    << 250 Ok
    ERROR: Transaction failed: Expected ';', got "message"

    1. That error means that the details inputted in the SMTP test tool has returned invalid. Please check your SMTP details.

  13. Can you help me?
    In my test there was the return below:

    ERROR: Unexpected token at offset 38

    LOG below:

    Connected to smtp://email-smtp.us-west-2.amazonaws.com:25/?starttls=when-available
    <> EHLO []
    << 250-email-smtp.amazonaws.com
    << 250-8BITMIME
    << 250-SIZE 10485760
    << 250-STARTTLS
    <> EHLO []
    << 250-email-smtp.amazonaws.com
    << 250-8BITMIME
    << 250-SIZE 10485760
    << 250-STARTTLS
    <> AUTH PLAIN ********************
    << 235 Authentication successful.

    1. Hi Tiago,

      We’re not showing an active GMass account under the email address you used to make this comment. You may contact our support team directly by going to gmass.co/g/support so we can assist you directly.

  14. Can anyone explain why I’m getting this? “ERROR: A connection attempt failed because the connected party did not properly respond after a period of time, or established connection failed because connected host has failed to respond”

    1. Hi Akter,

      That error is due to the SMTP server not responding. Please contact our support team (gmass.co/g/support) so we can assist you directly in troubleshooting.

  15. Have a nice day. I successfully send with Smtp tool on my own mail server. But I can’t send it via sendmail function that I wrote in asp.net c #. What library or structures do you use in your source code? Can you even give it a hint?

    1. Hi Pramod,

      The easiest way to proceed is to verify the “from” address that you’ll send campaigns from in your Gmail account. That way you can avoid complex DNS entries and your emails will still be SPF and DKIM compliant. As soon as you log in to your SendGrid account, you’ll be directed to verify a sender, so proceed with that before setting up the API.

  16. ERROR: A connection attempt failed because the connected party did not properly respond after a period of time, or established connection failed because connected host has failed to respond

    1. Hi Hasan,

      SendGrid recently made it a requirement to connect to your SendGrid account using a generated API key. Upon checking, your SMTP account is connected to GMass using your SMTP Username and Password which is why your SMTP is not functioning as it should.

      Please log into your SendGrid account and generate an API key for use with your GMass account and then set this newly generated API key to your GMass account as seen in this article:https://www.gmass.co/blog/sendgrid-smtp-account-configuration/#post-1883:~:text=This%20is%20how%20you%20will%20set%20the%20Sendgrid%20server%20to%20be%20used%20in%20GMass.

  17. verification currently unavailable pls solve this solution and this site is very good i like it but verification problem please solve this problem and it’s totally free

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