send bulk emails from SMTP exchange server to internal domain

Mohamed Ahmed Arida 21 Reputation points

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

    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:


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  1. Mohamed Ahmed Arida 21 Reputation points

    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.


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