Freshdesk will allow tickets to be created even when the attachments are exceeding the limit - from the email service, we now allow tickets which have attachments upto 50MB to come in, however, all attachments above 20 MB limit will be dropped and this alert will be shown in the ticket - 'Attachment(s) that exceed 20 MB limit have been dropped. Please reach out to the sender.'
This way, the tickets get created and the agents are also notified about the status of the attachment(s).
Note: The limit is 20 MB for Blossom and above accounts. For Sprout and trial accounts, the threshold is 15 MB.