In the past, I have built things simular to what you are wanting to do. A couple of things that I would suggest:
It would be simpler and faster when attempting to locate the emails you need to process if you can set up a special email address to which these emails can be sent or at least set up some process to move all eamils with a specific subject line to a specific folder. It can be done having the emails come into your normal email address but if you used an email address with lots of other email comming to it, you will have to do much more verification that the email has everything you will need. Also using the special email address or special folder makes it more simple check for and untimately to verify that there are new emails to be evaluated because each time you find a new email and process it, you can then move that email to a "processed" folder.
You can use the Timer and timer event to check for new emails in the specified inbox/folder.
All you need is that the subject line be the same in each email. You can use that to verify that the email in question is one you need to evaluate further.
Next, of course, you will have to check to see that there is an attachment of the type you are looking for and then save the attachment to a specific location. (Here I would assume that all attachments are in the same format and with some naming convention.)
Once the attachments are saved to a specific location with an expected naming convention, then you simley import the new records, appending them to the existing table or if you need to do some processing of the data before appending the records to the final table, you could have the imported data placed into a temporary holding table, do your processing and then append the data to the actual table.
Just my thoughts.
