send bulk emails from SMTP exchange server to internal domain

Mohamed Ahmed Arida 21 Reputation points
2021-12-06T04:38:57.663+00:00

we are in Education environment that deals with more than 500,0000 students accounts, we plan to send notifications to a part of them (around 60,000 students) of their exam results.
we plan to do this by using on-prem Exchange (Version 15.1 (Build 2176.2)).
all emails will send to students internal domain e-mail. we will not send any e-mail to External domains.
we have office 365 hybrid setting configuration and all students mailboxes and sender email on office 365 cloud.
I put the sender email to the spam filter allowed list.
I'll use a PowerShell script to run this task.
is there any limitation on sending emails from on-prem exchange server? is there any concerns that i need to be awarded?

Exchange Server Management
Exchange Server Management
Exchange Server: A family of Microsoft client/server messaging and collaboration software.Management: The act or process of organizing, handling, directing or controlling something.
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  1. Andy David - MVP 138K Reputation points MVP
    2021-12-06T13:10:29.32+00:00

    That will be throttled at that level. There is a high possibility it will get blocked as well.
    I would recommend breaking it up and sending these out through out the day instead off all at once and watch for any rejections.

    Please see the sending limits:

    https://learn.microsoft.com/en-us/office365/servicedescriptions/exchange-online-service-description/exchange-online-limits#sending-limits

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  1. Mohamed Ahmed Arida 21 Reputation points
    2021-12-07T04:46:07.817+00:00

    Thanks @Andy David - MVP
    This means that if I need to send 60,000 email, I need minimum 6 users mailbox (send users) and keep the sending rate to max 30 email per minute.

    right?

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