When transferring a snapshot between accounts (using this feature https://www.digitalocean.com/company/blog/easily-transfer-snapshots-between-accounts/), the recipient of the share does not currently getting an email notifying them that a snapshot has been shared with them. I suggest that the recipient of the share receives an email letting them know where to transfer the snapshot into their account.
I recently tried to transfer a snapshot with a client and the process took several days because we both assumed that my client would get an email when the share occurred.