Im currently working with exchange server 2013, and i need to configure my server to only allow mail with attachments larger than 5mb to be sent only between the hours of 6pm and 8am.

I set a rule to block attachments larger than 5mb to be sent, but i cannot figure out how to allow them to be sent between those specific hours.

create two scheduled tasks to disable and enable the the transport rule at the hours you desire: https://technet.microsoft.com/en-GB/library/bb125180%28v=exchg.150%29.aspx?f=255&MSPPError=-2147217396

Worked Thank you