detect that an email is sent to a mailing-list

Question

My application sends mails containing an authentication token. The user which receives the mail clicks on a link and is directed to a webpage. The app recognizes him.

The problem is that sometimes the mail is sent to a mailing list instead of a personal address. Then several people come on the page and override each others' actions.

There are 2 ways I think I could solve this :

1. detect that the email address is a mailing list before I send the mail
2. include the final recipient address in the link in the email.

Is any of the 2 possible ?

Answer 1

No.

The recipient can tell if the message came from a mailing list (if the list follows the right guidlines), but the sender can't.

There is no way for the sender to modify the body of an email dynamically based on the final recipient.

Answer 2

David's answer is correct. Though, depending on your context you may find the following idea useful:

You might be able to record the number of clicks per email sent out using that token and just specify a threshold. If the number of times the auth token exceeds it, flag the recipient as a mailing list and exclude them from future mailings.