Exchange 2016 unable to upload large attachment

Whenever I try to upload attachment, it always prompt "The following files weren't attached because adding them would cause the message to exceed the maximum size limit of 25 MB: 0520.zip." 

I also set the maxsendsize and maxreceivesize to 100MB respectively but no luck though. Reset IIS and reboot the server and getting same result too. 

Anything I missing here and couldn't figure it out. 

Thank you all.