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

Emails to gmail addresses suddenly return undeliverable

  • 5 replies
  • 8 have this problem
  • 12 views
  • Last reply by david

more options

Emails to gmail addresses return undeliverable. I receive this message:

Action: failed Status: 5.7.26 Remote-MTA: dns; gmail-smtp-in.l.google.com 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 [my email address] 550-5.7.26 did not pass with ip:
   [23.83.218.247]. 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.
   d2-20020a170902aa8200b001aaf5dcd774si19262143plr.173 - gsmtp

Any assistance would be appreciated. Thanking you.

Emails to gmail addresses return undeliverable. I receive this message: Action: failed Status: 5.7.26 Remote-MTA: dns; gmail-smtp-in.l.google.com 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 [my email address] 550-5.7.26 did not pass with ip: [23.83.218.247]. 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. d2-20020a170902aa8200b001aaf5dcd774si19262143plr.173 - gsmtp Any assistance would be appreciated. Thanking you.

All Replies (5)

more options

The information is that your email domain cannot be authenticated. You may wish to check with your email provider to fix this. The references to DKIM and SPF are server configuration settings, in no way related to Thunderbird.

more options

Thanks for your reply. Why would it be that its only gmail addresses that won't accept my emails? Regards, Brendan.

more options

It may be that Gmail has more security checks.

more options

Thanks for your reply David. Last question: why did this happen randomly? I used to be able to send emails to any email address? Regards, Brendan.

more options

We see several posts on changing security among email providers. I agree this can be confusing, but it's a sign of continuing security concerns.