Exchange 2016 attachment size limit settin
Open Exchange Management Shell to view the global attachment size defaults to 10MB
Get-TransportConfig | Format-List MaxReceiveSize,MaxSendSize,MaxRecipientEnvelopeLimit
Set organizational limits in mail flow (default: 10MB)
Change to 25MB attachment size
You need to restart the Microsoft Exchange Information Store service to take effect.
Since the default attachment size limit for send and receive connectors is 36MB, the maximum global attachment size is 36MB, if 36MB is exceeded, you also need to change the default attachment size limit for send and receive connectors.
