If you would like to update a database table by sending an email, one of the options that would appear to be appropriate is that you can actually send an email to an established email address/mailbox. Then, with a program, have it routinely log into the email mailbox and when there is an email present, retreive it, parse it, then take the infromation extracted from the message and upload it to the DB table. This can easily be done using POP3, many programming languages have libraries/built-in methods to do this.
This would require that the email itself has content in a standardized format. For example, the subject line may require some flags present or something that your program could recognized. Same goes for the content. You need your program to read through the content so it can retreive the content and know how to take that information and upload it to the proper fields.