2024: Gmail users not receiving notifications from OJS3

Description of issue/problem:
I am the editor of a journal published by a university Press since 2020.
I just realized that gmail users (registered with a gmail address) in our OJS are not receiving any notifications from the journal’s OJS Platform: ojs@univnamepress.org . I have recently (las week) checked this issue with 3 authors who are gmail users in our journal’s OJS. The message is not in Spam or Junk in their gmail.
Then I registered myself in OJS3 with my personal gmail and sent requests for reviews to myself’s gmail. I did not receiving anything and nothing was in Spam, Promotions, etc.
There is a pattern: those users with gmail are not receiving anything from us. And I am afraid this has been happening for months but I assume people were just not responding.
I checked the PKP forum on OJS3 but they talk about a configuration I have no clue for. The overall pattern is “email configuration” and specifically with gmail accounts. Can you help? I have spent a good time reading PKP forums and still does not understand what to do:
Here another example of the gmail issue:
OJS 3.4 SMTP Email not sending email notification to users
[07:48] Quispe Agnoli, Rocio

Or: https://docs.pkp.sfu.ca/admin-guide/3.3/en/email (I have received notifications–in my gmail-- from ojs@msupress.org up to last year but not anymore).

I am now very concerned because this is a pattern with gmail users and I wonder for how long this has been happening.
Please, help or advice?

Steps I took leading up to the issue
See attached as an example of a notification sent to someone with gmail. It is recorded in the activity log but the person (gmail users) never got it. We have tried 10 different notifications with 3 users last week, same issue.

What application are you using?

Additional information
See attached–example of a notification sent to gmail user from our OJS–but user never received it. Not in Spam, Promotions, etc.

I’d bet that has to do with spf records. Basically for most email domains there’s a list of servers that are allowed to send them (and apps such as OJS are rarely on this list). This was not enforced for long but gradually more and more sites do.

If that’s the case you’d either get your OJS on this list or use an smtp server (and likely need to do all this envelope sender configuration).

Thanks much for your advice. I am not in charge of OJS configuration or SMTP servers. Then, excuse my naive questions to confirm two possible solutions:
(1) SPF records: Define your SPF record - Google Workspace Admin Help The OJS notifications to Gmail users–as far as I have tried–don’t even appear in their junk or spam email. They simply do not make it. Is the idea to put our OJS in the Gmail domain server (“get your OJS on this list”)?
(2) “or use an smtp server (and likely need to do all this envelope sender configuration).”

Unfortunately misconfigured emails can be simply dropped without a trace.

I’d suggest try the smtp solution first. it’s all about the email section in the config file
The template is quite well documented.