Invalid HELO Name (Email Authentication)

SMTP authentication is required for all outgoing emails on our servers. Customers using an email client such as Thunderbird, Outlook, or Mac Mail (Apple Mail) may be affected if they do not have the authentication properly set for the outgoing server. If you are receiving “550 Access denied Invalid HELO name” (or a similar error message) in your email client, please check your settings as follows:

Enabling SMTP Authentication

To resolve this error, you simply need to enable SMTP Authentication in your email client. The instructions below will provide the steps to do this for a few common mail clients.

Microsoft Outlook 2010 / 2013

  1. From the main Menu Bar, Click the File tab.
  2. Click the Info tab on the left and click on Accounts Settings
  3. Select your email account then click Change.
  4. Click More Settings.
  5. Select the Outgoing Server tab.
  6. Click on the box beside My outgoing server (SMTP) requires authentication.
  7. Select Use same settings as my incoming email server.
  8. Click Ok.
  9. Click Next.
  10. Click Finish.

Microsoft Outlook 2007 and earlier

  1. From the Menu Bar, click Tools then click E-mail Accounts.
  2. Select View or change existing e-mail accounts then click Next.
  3. Select your email account then click Change.
  4. Click More settings.
  5. Select the Outgoing Server tab.
  6. Select the box beside My outgoing server (SMTP) requires authentication.
  7. Select Use same settings as my incoming email server.
  8. Click Ok.
  9. Click Next.
  10. Click Finish.


Note: These instructions are based on Thunderbird version 68.6.0 (32-bit)

  1. Click on the Mail account that you are working with. Note that you can have more than one account in Thunderbird. this will bring up the main menu for Thunderbird in the middle of the screen.
  2. Click on View settings for this account.
  3. This will bring up the Account Settings window where you can click on Outgoing Server (SMTP) at the bottom of the list on the left side of the window.
  4. Select the appropriate outgoing server and click the Edit button in the window that appears.
  5. Make sure that the Authentication method is set to “Normal password“.
  6. Click OK to close the SMTP edit window and again on the Account Settings window.

Mac Mail

  1. From within Mac Mail click Mail > Preferences > Accounts.
  2. Click on the account you’re working with.
  3. Click on the Server Settings tab, then look for Outgoing Mail Server (SMTP).  You may need to uncheck the box labeled Automatically manage connection settings. Click the drop-down arrow next to your account name and select Edit SMTP Server List.
  4. Under Server Settings, find Authentication and make sure it is set to “Password“.
  5. Click OK to close the edit window
  6. Then click on the Save button to save your changes.
Arnel Custodio Content Writer I

As a writer for InMotion Hosting, Arnel has always aimed to share helpful information and provide knowledge that will help solve problems and aid in achieving goals. He's also been active with WordPress local community groups and events since 2004.

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44 thoughts on “Invalid HELO Name (Email Authentication)

  1. Hello, i am still getting the below error once i followed the insutrcutons on how to fix it (altough  the settings were in place already). How can i fic this. It just started today

    Your message did not reach some or all of the intended recipients.


          Subject:    FW: Closing Department- File Received- Somers

          Sent: 12/27/2017 3:53 PM


    The following recipient(s) cannot be reached:


          ‘[email protected]’ on 12/27/2017 3:53 PM

                550 information, please see




    1. That message appears to be generated by the InMotion Hosting filters that prevent Spam from degrading the quality of service in regards to the ability to send emails. I recommend you contact our 24 / 7 / 365 Live Support for further assistance. With the necessary account verification and details (email address that is sending and receiving) you provide to them, they will be able to review the server logs to ensure that mail is being handled by the server properly and assist you further with this specific issue.

      1. My Outlook is IMAP so I can’t set this the way you suggest. No SMTP options when editing account settings at all. This is so annoying. For 2 months we cannot establish serious business because of you, but we have to use yahoo instead. Really? We also cannot access live support because we cannot access whatever AMP is with our email address and password. Really? Well, now you can ask yourself why yahoo and gmail are big in this business…

        Please do something immediately so we could send emails without 550 errors!!!! We have a saying: a good voice is spreading far away, but bad one is spreading much more farther…

        P.S. Oh, Gosh. To post here it’s even not enough to type url without typing https://www. only by domain. Bah…

      2. I’m sorry you’ve been having issues with your email. I’ve reached out to our technical support team on your behalf and someone will be in touch to assist you and resolve the issue.

  2. Hi — I tried your SMTP resetting solution and it didn’t work.  In fact, my Outlook was already set that way and I’m still getting the bounceback ” “550 Access denied – Invalid HELO name” messages.  Any further suggestions?

  3. Having the exact same problem trying to respond to a potential customer who contacted me via gmail. Bouncing with the 550 error. I already have SMTP authenication on the latest version of Outlook.

  4. some of our staff link our official email with Gmail and recently we found we can’t send out the email to our partners which we always contact them via email. The email was classified as spam with the following message, for example
    Final-Recipient: rfc822; [email protected]
    Action: failed
    Status: 5.0.0
    Remote-MTA: dns; (, the relay for
    the domain.)
    Diagnostic-Code: smtp; 550-This message was classified as SPAM and may not be delivered. For more
    550 information, please see
    Last-Attempt-Date: Tue, 14 Mar 2017 04:31:23 -0700 (PDT)
    We refer to this page,, but it didn’t show how we can set up in Gmail or how we can avoid such error.


    1. Hello Chuck,

      Sorry for the problem with your outbound email coming back as spam. All outbound email is being filtered and checked for spam, but there is a possibility that your email is being flagged incorrectly. Please submit a support ticket to our technical support team (through your Account Management Panel (AMP)) and they will review the email to see why it’s happening. They can also whitelist your address to keep it from happening. Please submit the ticket with a sample of the email text and they can take care of it.

      If you have any further questions, please let us know.

      Kindest regards,
      Arnel C.

  5. well, I checked my Thunderbird, and settings are like you instruct,  yet I still cannot in 20 tries get an email out.  Gmail didn’t have a problem sending it, but now when her replies I’ll hafta go chasing.

    Have any other suggestions about where to look fo rthe trouble ?

    1. Hello Herb,

      Sorry for the problem with sending email from your Thunderbird email client. If you are having a problem with sending out emails, we would need a little more information to be able to help you resolve the issue. Specifically, if you could provide the settings you’re using and the domain for and email account that is having the issues, then we can investigate the issue in more depth if you are an InMotion Hosting customer. You can also refer to this tutorial for help in troubleshooting the issue. If you want to handle the matter privately, please contact our live technical support team via phone/chat/email. Note that all the replies on the support center website are public.

      If you have any further questions or comments, please let us know.

      Arnel C.

  6. I followed the instructions for the email authentication described above and my account was already set up that way.  It still won’t send emails, but I can receive them.  It was working fine one day and the next it no longer sends emails.  Next suggestion please? 

    1. Remember some email clients will require username/password authentication for incoming and outgoing messages. Make sure that both of these specifications have the correct credentials.

  7. Hi,

    I am unable to see any incoming emails in the Outlook on my PC.  The received emails are displayed on the webmail and my phone.  To make things even stranger, I can send out emails from my Outlook and the recipient receives them ok but once they reply, the email does not come to my Outlook.  I have checked my setting million of times and I also tried deleting the account and recreating it from scratch and it still didn’t help.  I also tried to use different numbers for the outgoing/incoming servers – with no luck.  Can you help me, please?

    Thank you,


    1. Hello Bozena,

      Have you tried using non-SSL and SSL settings? Are you getting any error while trying to perform a send/receive in Outlook? When did this start happening?

      Best Regards,
      TJ Edens

  8. Hello-

    I work at a company that uses a portal for users to register on and the system automatically sends them a User ID and password to access the system. Many times we will get this error sent back to us. Forgive the novice nature of the question but: — Is it the setting on OUR end that need to be changed or is it the settings on the person who is not getting the email delivered?

    Thanks for your help 

    1. Hello Paul,

      Most likely, the issue you’re seeing is the result of specific configuration settings missing from your email client. You may want to review your settings and then report any continuing issue to your network admin or email administrator. They will be able to identify the cause of that issue pretty quickly.

      Kindest regards
      Arnel C.

  9. This actually does not help me.  I am a Mac user and I use Outlook for Mac 2011.  These instructions are not the same as the settings options I have.  Can you please advise?

    1. Thank you very much sir for such a very informative information and helping to people like us.
      God bless you all sir, Good Luck.

  10. Hi Guys,

    I found this problem in a company of a friend and he said it was a problem with a dll of Windows. After recover this file the email returned to work.

    1. Hello Marcio,

      Thank you for the information. Would you be willing t share a link to the file? It may help other people who see your post.

      If you have any further questions, feel free to post them below.
      Thank you,


  11. Thanks for such clear instructions on how to clear mail error. Whis my hosting company would be so helpfull 5* to you.

    1. Hello John,

      Thanks for the compliment! Let us know if you have any further questions or comments!

      Arnel C.

  12. Worked like a charm!  I printed and distributed the steps to the rest of the staff.  Why would this setting reset?


    Also, if traveling and using wi-fi, will the settings need to be changed?

    1. Hello BreeCass,

      I’m not sure why the setting would reset in your mail client, other than if you had re-created the local email account in your mail client and didn’t enable the SMTP authentication which is disabled by default in some clients.

      When traveling and using WiFi you shouldn’t need to change these settings. However depending on the WiFi you are using some require additional authentication to send mail, and some don’t allow outbound mail connections at all. In those cases it’s typically best to use webmail in your web-browser as a workaround.

      Please let us know if you had any further questions at all.

      – Jacob

  13. Hi JeffMa,

    Your solution to this problem was the first I came across after my e-mail messages suddenly started not getting sent (Outlook 2003), and it worked like a charm. THanks a million!

  14. Thanks for the help but can you please suggest why my emails were being sent fine yesterday with no non deliveries and then when I switch on today it behaves like this ??

    Rgds Gearóíd


    1. Nothing has been recently changed regarding email authentication on the servers, but your mail client may have stopped correctly sending authentication data. Does the message send correctly from within webmail? Do you have outgoing mail authentication enabled on your mail client?

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