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Unless your install is very big, 30 emails minute is not a low limit, maybe you should have a look at what notifications are being sent (for example you can choose to receive only mail related to you)

Hi Mr. Joan J

Thanks for your support.
I already thought about these settings but in my project, sometimes they add watchers or assign to group to check the issue. And when they update multiple issues, the limit 30 per minutes is not enough.

It seems that the limit is fixed on microsoft part (https://learn.microsoft.com/en-us/answers/questions/261878/office-365-mail-sending-limits), the easiest solution would be to configure an intermediate smtp server that would retry the sending of the emails that where refused.
You can look for smarthost configuration for your email server.

You can go for any 3rd party paid SMTP provider such as Sendgrid, mailgun or any other provider.

Once the DNS records are set on your domain, you can use their SMTP account with redmine.