Disposable Email Addresses with Postfix

As I thought about setting up my website and email, I wanted to have a way to give out disposable email addresses. That way, I can give Widget Co an email address unique to them, and I can know if they sell my email because I will get emails from Sprockets Inc. at my address for Widget Co. In that case, I can trash all email sent to that address, eliminating that spam.

A Possible, but not Ideal Option

I know of a couple people who use the following system: they set up a catch-all email for their domain, and point it at their main inbox. Then, they give name@domain.com to people they want to communicate with, and they give business_name@domain.com to businesses they need to communicate with. In my example, they would give widget@domain.com to Widget Co.

However, there are a couple problems with this system.

  1. Spam. They receive all the spam that is sent to any address at their domain. Granted, they could use spam filtering to solve this, but wouldn’t it be better if it just bounced?
  2. Plausible deniability for the company. It is conceivably possible that a spammer could have made up that address from a dictionary, or someone could have done so deliberately. I would prefer to have a stronger reason to claim that a company sold my email.

A Better Option

Another option would be to set up an alias pointing to the main email for every company you want to communicate with. This has the advantage of dramatically reducing the spam problem, and depending on how creative you get with the addresses you give out, it could potentially address #2 above as well.
However, this option has a flaw that caused me to write it off. That is that you have to manually create an alias for every address you want to give out. The huge advantage of the first option is that you don’t have to pre-plan or keep a list of the addresses you give out.

My “Ideal” Option

As I thought about it (this is before I even had a domain name, so it was purely theoretical), I came up with the idea that maybe I could combine the company name with some sort of hash of the name and a constant secret, so that the disposable email would only be delivered to my inbox if the hash matched its expected value.

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