In salesforce, can you verify that an email sent by a workflow was opened by the recipient?

Question

I am using a salesforce workflow to send out product information and invoices to clients but I am running into problems thinking of how to verify if a client receives the email and or opens it. Is there any way to prove that a client received my inventory list or invoice? Doing some prior research on this subject I have come across the following suggestions:

1. Adding a 1x1 invisible image to the email with a unique id
2. Adding a regular image instead of a 1x1, maybe company logo
3. Having the recipient click a link to see the invoice

With all these solutions, you have to detect image requests or link request for them and extract/produce a unique id for each client. I am not really sure how to do this in salesforce so any help would be appreciated, along with other detection ideas.

Answer 1

If you have Salesforce Content, there are some ways to expose documents to clients with the features you need. Basically you'll send an email with link and later you can track confirmation of opening, count how many times was it downloaded.. You can also set the expiration date to the document (can't be downloaded anymore after the date).

As for "pure" email from Apex/Visualforce and basically manually recreating the Content's functionality... nowadays most mail clients block external pictures unless explicitly allowed by the mail recipient, so I suspect you'll have poor track of emails marked as opened. Probably you could create a small Visualforce page (no header, no styles, just controller that makes update "invoice viewed" in the database). Display image from Documents on this page (make sure it's "externally available image") or even just display 1 pixel encoded in base64...