I'm pretty sure the email is sent to the correct email address, as this is stated when trying to log in: "Enter the code that was sent to j@xxxxx.org within 5 minutes." (email address redacted by me)

I triple checked junk, spam, trash and normal inboxes, both in Thunderbird and the web client to my email, but I do not see the email with the code.

Have you added the address mentioned to your contacts? It seems it may be necessary. See the first link on the following article.

https://support.mozilla.org/en-US/kb/im-having-problems-confirming-my-firefox-account

Have you added the address mentioned to your contacts?

I tried this, but it does not make any difference.

As a test, I tried now to set up a secondary email address to my Firefox account. Setting this up requires me to provide the secondary email address. Next, I'm asked: "Please enter the confirmation code that was sent to ⁨jan@yyyyyyy.nl⁩ within 5 minutes." (email address redacted by me)

But also on this email address I do not get an email with confirmation code.

Could it be that the Firefox accounts service is disrupted? Or could there be something wrong with my Firefox Sync account?

As another test, I tried a protonmail address for my secondary email address. Here I did receive the confirmation code. So somehow the emails to my personal domains are not delivered.

I got this reply from my internet provider (translated by me):

"The domain firefox.com has a wrong DMARC record and therefore the mail is rejected. On this external website you can see that the DMARC record is not correct: http://h2g.cc/J5mrUs. A semicolon is missing behind the part "aspf=r". At firefox.com they have to adjust this."

Where can I inform Firefox about this issue?

I got this reply from my internet provider (translated by me): "The domain firefox.com has a wrong DMARC record and therefore the mail is rejected. On this external website you can see that the DMARC record is not correct: http://h2g.cc/J5mrUs. A semicolon is missing behind the part "aspf=r". At firefox.com they have to adjust this." Where can I inform Firefox about this issue?

There's an email address in the following article. Unbelievably, the email address itself requires moderator approval.

https://support.mozilla.org/en-US/kb/im-having-problems-confirming-my-firefox-account

There's an email address in the following article. Unbelievably, the email address itself requires moderator approval. https://support.mozilla.org/en-US/kb/im-having-problems-confirming-my-firefox-account

Actually it was the links in the quote that flagged the posts.

Mozilla does not have one on one support by email, chat or phone for their Firefox web browsers.

That email address mentioned was for to make sure you can receive automated email related to Firefox Accounts and not have address flagged as spam.

Another user, it seems, has the same issue.

https://support.mozilla.org/en-US/questions/1419341

Yes that's me, I'm also having the same trouble. There must be some sort of glitch and I hope to find a solution. Not having access to over 5 years of bookmarks is really setting me back in my work.

I opened a support request, and Firefox Accounts fixed the problem. I do receive the email with the six letter code now.

Jan, how did you create a support request? I haven't bee able to find a way to do so...