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

Can't send to gmail accounts

  • 4 replies
  • 3 have this problem
  • 190 views
  • Last reply by david

more options

Suddenly, neither my wife or I can send emails to anyone with a gmail.com address. I even tried sending one to my own gmail account and it failed. We're both using the most current version of Windows and version 102.11.2 of Thunderbird. Here is failure message.

Diagnostic-Code: smtp; 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 [montanapens.com] did not 550-5.7.26 pass with ip:
   [146.20.161.78]. 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.
   i21-20020a05620a151500b0075c984c68d1si3680713qkk.545 - gsmtp
Suddenly, neither my wife or I can send emails to anyone with a gmail.com address. I even tried sending one to my own gmail account and it failed. We're both using the most current version of Windows and version 102.11.2 of Thunderbird. Here is failure message. Diagnostic-Code: smtp; 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 [montanapens.com] did not 550-5.7.26 pass with ip: [146.20.161.78]. 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. i21-20020a05620a151500b0075c984c68d1si3680713qkk.545 - gsmtp

All Replies (4)

more options

Please share this with your email provider. Google has tightened security on email and many personal domains are not fully configured for security. Your email provider can make the appropriate DKIM and SPF changes.

more options

Thanks, I will call them tomorrow.

more options

I got a similar message : [edited] @gmail.com

   host gmail-smtp-in.l.google.com [142.251.163.26]
   SMTP error from remote mail server after end of data:
   550-5.7.26 This mail has been blocked because the sender is unauthenticated.
   550-5.7.26 Gmail requires all senders to authenticate with either SPF or DKIM.
   550-5.7.26
   550-5.7.26  Authentication results:
   550-5.7.26  DKIM = did not pass
   550-5.7.26  SPF [sympatico.ca] with ip: [67.215.8.22] = did not pass
   550-5.7.26
   550-5.7.26  To mitigate this issue, please visit Gmail's authentication guide
   550-5.7.26 for instructions on setting up authentication:
   550 5.7.26  https://support.google.com/mail/answer/81126#authentication h4-20020a05620a10a400b0076cb1c1cd67si8559603qkk.655 - gsmtp

As suggested above, I contacted Sympatico and they said the problem was with Thunderbird. Now what?

Modified by James

more options

Unfortunate that some email provider tech support personnel deny problems. You might try this site at https://www.alitajran.com/check-spf-dkim-dmarc/ to see if their testing can help prove the problem - but I have not used the service myself.