This site will have limited functionality while we undergo maintenance to improve your experience. If an article doesn't solve your issue and you want to ask a question, we have our support community waiting to help you at @FirefoxSupport on Twitter and/r/firefox on Reddit.

Search Support

Avoid support scams. We will never ask you to call or text a phone number or share personal information. Please report suspicious activity using the “Report Abuse” option.

Learn More

Sending emails to Gmail users

  • 3 replies
  • 1 has this problem
  • 3 views
  • Last reply by david

more options

Hello, our company has used Thunderbird Email for a long time but as of yesterday we are unable to send any emails to anyone who has a Gmail email address. I have tried looking up what we can do but have not had any luck and still cannot understand what the issue is. It says: <<< 550-5.7.26 This message does not have authentication information or fails to <<< 550-5.7.26 pass authentication checks. To best protect our users from spam, the <<< 550-5.7.26 message has been blocked. Please visit <<< 550-5.7.26 https://support.google.com/mail/answer/81126#authentication for more <<< 550 5.7.26 information. dd5-20020a1709069b8500b006a744d0cdeesi274130ejc.875 - gsmtp 554 5.0.0 Service unavailable

This is happening when we are sending automated emails as well as individual emails we are typing and sending. Please let us know if there is any way you can provide some support. Thank you!

Hello, our company has used Thunderbird Email for a long time but as of yesterday we are unable to send any emails to anyone who has a Gmail email address. I have tried looking up what we can do but have not had any luck and still cannot understand what the issue is. It says: <<< 550-5.7.26 This message does not have authentication information or fails to <<< 550-5.7.26 pass authentication checks. To best protect our users from spam, the <<< 550-5.7.26 message has been blocked. Please visit <<< 550-5.7.26 https://support.google.com/mail/answer/81126#authentication for more <<< 550 5.7.26 information. dd5-20020a1709069b8500b006a744d0cdeesi274130ejc.875 - gsmtp 554 5.0.0 Service unavailable This is happening when we are sending automated emails as well as individual emails we are typing and sending. Please let us know if there is any way you can provide some support. Thank you!

All Replies (3)

more options

This is generally the issue when the receiving mail supporter (in this case, Gmail) cannot confirm that the sending domain matches the domain of the host sending site. For example, if your business is cakes.com and your business hosting provider is bluehost.com, Gmail sees that the actual host domain is bluehost and looks for confirmation that the settings for cakes.com are reflected there. This ties to DKIM and SPF settings on the server and are beyond anything TB can do. My suggestion is to check with your hosting provider.

more options

Hi David, Thank you for your help. Thunderbird does not offer any support so I am wondering if we need to find a new place to use our company email as it is just an info@businessname.com email address. I am assuming our "host" is Thunderbird? Sorry I am somewhat knowledgeable but not enough apparently haha. I am also not sure about DKIM or SPF settings. But if Thunderbird is considered our host is there another one that is free to use that you would suggest for us to be using instead? We have never had this problem until this week and have been using it for quite some time now. If you are unable to provide anymore suggestions, thank you again for what you have given us!

more options

Someone in your company is paying someone for the use of that domain name and for providing an email account. That person can direct you to getting this resolved. TB is not a host. All TB does is retrieve mail from the account and send messages via the account. There is no need to change from TB, as it is working properly. DKIM and SPF are technical terms that you (and I) don't need to know and are used by the web hosting company. This is probably a simple fix, once you notify them.