Reply I cannot type

"You were saying “And sometimes at registration stage, PlayStream shows the email is sent.”, so do you mean that sometimes there is no “email_sent” event generated after you successfully called the AddorUpdateContactEmail API (the contactEmail passed to the EmailAddress parameter it is not empty, and the response returns “OK”), the “player_updated_contact_email” event was also generated too. If that’s the case, it’s possible that there is something wrong with the Rule system ( the “player_updated_contact_email” event somehow didn’t trigger the “Send email” Action), could you please provide us your title id and the PlayFabIds of those associated players for us to investigate?"

I mean that "email_sent" event is not generated in the PlayStream or the history of events, the EmailAddress parameter is not empty as I check from debug console and put debug line in every step of the process to make sure this is not our code's problem.

Rule system is set as instructed in the tutorial. I will attach the rule screen. (my guess is it is triggering anti-spam measures on the PlayFab side and its not sending the email.)
https://i.gyazo.com/8e4ce82ba858957add0ccd920b9da6ef.png

"You were saying “Sometimes, the registration is a success, but the Contact Email Address is empty.”, do you mean that the Contact Email field is empty after you successfully called the AddorUpdateContactEmail API (the contactEmail passed to the EmailAddress parameter it is not empty, and the response returns “OK”), like this:"
If that’s the case, there are several possible reasons for this:

The AddorUpdateContactEmail API request failed, you may need to check the error messages for more info.
There is a time lag before the contact email gets actually updated in the PlayFab backend, you may need to wait a while before accessing it.
Yes, Contact Email field is empty before and after the AddorUpdateContactEmail API.
request.EmailAddress is not empty, I am passing correct email address, and checked that SendEmailTemplate from API works at sending email to the set address, but AddorUpdateContactEmail API fails.... silently.
The API returns success but it has failed to update the field.

"You were saying “Worse is that the AddorUpdateContactEmailRequest fails if the email is empty, so... it doesn't send any email.”, as I see it, it’s quite reasonable: EmailAddress is a required property in the AddOrUpdateContactEmailRequest, hence error will occur if it’s empty. And it's possible that the “player_updated_contact_email” event won’t get generated given the fact that the AddorUpdateContactEmail Request failed, so the “Send email” action won’t be triggered."

It is never empty because we don't send the request if it is empty. If the ContactEmail field of the profile is empty, we set a user login email to the EmailAddress and make the request. And request always returns success message, no error.

"You were saying “So, instead of that function, …, nothing happens on the PlayStream...”, from my understanding, you can confirm that the contact email was added to the player’s profile using GetPlayerProfile with ShowContactEmailAddresses in the PlayerProfileViewConstraints set as True before calling SendEmailFromTemplat to handle the empty contact email issue.
(Yes we set it eactly as it is)
What does “this also fails when you click the confirmation URL... it's not the same function as AddorUpdate” mean? What will happen if you click the confirmation URL, could you please be more specific? Moreover, you can go to [Game Manager] -> [Data] -> [Event History] to see the latest playstream events, please note that it usually takes a while (few minutes) before accessing generated events.

You were talking about the broken confirmation link, what does it behave? Could you be more specific?"

The SendEmailFromTemplate API call sends template email with some confirmation token, which if you click, it says "tocken error" and nothing happens.

"About the issue: AddOrUpdateContactEmail returns success, however, the playstream logs no "sent email" action performed and the email is not sent at all, could you provide some info to prove this issue? And it would be helpful if you can provide your title id and the PlayFabIds of those associated players for us to investigate, thanks."

Title ID is written on the reply comments below.

Thanks.
I believe this is a problem on the API, at least it should return error if it failed to update the field.