why exchange on premise cannot receive mails event if attachment limit is 60MB

is your exchange server connected directly to the internet? Or do you route mail through a spam firewall device? That device must also allow send/receive maximums.

There are multiple levels on which you need to update limits for larger attachments, as detailed here: https://technet.microsoft.com/en-us/library/bb124345(v=exchg.150).aspx

 

 In addition, there are some client-specific limtis: http://technet.microsoft.com/en-us/library/hh529949(v=exchg.150).aspx