exchange2016 mailbox receive message size limit 100MB and organization transport setting of max receive message size 30MB, how to allow user receiving 50MB Message

Question

Hi experts,

organization transport setting of max receive message size limits has been 30MB since exchange 2016 installation,
2 days ago, exchange 2016 mailbox receive message size limit of a user was increased from blank-setting to 100MB,
but now the user still can't receive message with size of 33MB.

is it true that user mailbox size limit takes precedence over all other max receive message size limits?

if so, why he user still can't receive message of 33MB that is smaller than user's mailbox limit 100MB?
what other limits or restart exchange services need to do ?
how to allow a special user receive messages larger than the org standard/default limits?

Any suggestion would be greatly appreciated.

Thanks for your time

pingatwork

Answer 1

Hi @Pingatwork ,
1.I agree with what udara said. The reason why the mail cannot be received is because it is larger than the organization limit. And if you have not made specific settings, the message is larger than the mail size that the default accept connector can received.

2.According to the part of “Order of precedence and placement of message size limes” in the link provide by udara, we could know that “Recipient limits between authenticated senders and recipients (typically, internal message senders and recipients) are exempt from the organizational message size restrictions. You can allow specific mailboxes to send and receive larger messages than the rest of the organization by configuring custom send and receive limits for those mailboxes.For messages sent between anonymous senders and recipients (typically, Internet senders or Internet recipients), the organizational limits apply".

3.So if you receive the 50MB email from the internet, you could increase all restrictions on mail size in the Exchange organization. And it should be noted that for any message size limit, you need to set a value that's larger than the actual size you want enforced. This accounts for the Base64 encoding of attachments and other binary data. Base64 encoding increases the size of the message by approximately 33%, so the value you specify should be approximately 33% larger than the actual message size you want enforced.

4.According to Microsoft’s official recommendations, in order to avoid wasting system resources, it is recommended that you keep the same limits for all locations.
For more information you could refer to the link provide by udara.

----------

If the response is helpful, please click "Accept Answer" and upvote it.
Note: Please follow the steps in our documentation to enable e-mail notifications if you want to receive the related email notification for this thread.

Answer 2

Reason is the "organization transport setting of max receive message size limits has been 30MB"
Increase this value more than 33MB.
you can refer following for further details of message size limitation,
https://learn.microsoft.com/en-us/exchange/mail-flow/message-size-limits?view=exchserver-2019