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.

Avatar for Username

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

Ova tema je arhivirana. Pitajte drugo pitanje ako vam je potrebna pomoć.

Thunderbird will no longer send messages

  • 1 odgovor
  • 0 ima ovaj problem
  • 14 views
  • Posljednji odgovor poslao david

gavintaylordrums
gavintaylordrums
more options

Hi there! Thanks for your help. I have been using Thunderbird for my email client for my business for the past 3 years. Starting about 4 weeks ago, the outgoing emails I try to send do not go through and I get an error message saying "Mail delivery failed: retunring message to sender." This seems to happen primarily with gmail accounts.

The text in the failure email is below. Thanks for any help you can give!

- Gavin

"host gmail-smtp-in.l.google.com [142.250.102.27] 

   SMTP error from remote mail server after pipelined end of data:
   550-5.7.26 This mail is unauthenticated, which poses a security risk to the
   550-5.7.26 sender and Gmail users, and has been blocked. The sender must
   550-5.7.26 authenticate with at least one of SPF or DKIM. For this message,
   550-5.7.26 DKIM checks did not pass and SPF check for [gavinbowescounseling.com
   550-5.7.26 ] did not pass with ip: [66.96.186.8]. The sender should visit
   550-5.7.26  https://support.google.com/mail/answer/81126#authentication for
   550 5.7.26 instructions on setting up authentication. v11-20020aa7d9cb000000b0051bdef1df27si628503eds.406 - gsmtp..."
Hi there! Thanks for your help. I have been using Thunderbird for my email client for my business for the past 3 years. Starting about 4 weeks ago, the outgoing emails I try to send do not go through and I get an error message saying "Mail delivery failed: retunring message to sender." This seems to happen primarily with gmail accounts. The text in the failure email is below. Thanks for any help you can give! - Gavin "host gmail-smtp-in.l.google.com [142.250.102.27] SMTP error from remote mail server after pipelined end of data: 550-5.7.26 This mail is unauthenticated, which poses a security risk to the 550-5.7.26 sender and Gmail users, and has been blocked. The sender must 550-5.7.26 authenticate with at least one of SPF or DKIM. For this message, 550-5.7.26 DKIM checks did not pass and SPF check for [gavinbowescounseling.com 550-5.7.26 ] did not pass with ip: [66.96.186.8]. The sender should visit 550-5.7.26 https://support.google.com/mail/answer/81126#authentication for 550 5.7.26 instructions on setting up authentication. v11-20020aa7d9cb000000b0051bdef1df27si628503eds.406 - gsmtp..."

All Replies (1)

david
david
  • Top 10 Contributor
more options

This indicates a security error for your account, and can only be fixed by your email provider. Be sure to notify them of this, as the problem will not go away. Google has been tightening security recently and we see posts such as yours regularly.