Decommissioning old email addresses with FastMail

The first business email address I used, [email protected], now almost twenty years old, is the source of 95% of the spam I receive. I no longer use this address, and would simply like to kill it, but every now the arrival of an important message reminds me that decommissioning it could result in missing something important.

Our company uses FastMail for email hosting, and the account has several domains aliased, including makalumedia.com. Chatting with FastMail support, I discovered that I could use their advanced “Sieve” support to effectively kill the address without risking to miss important emails.

Here’s how I did it:

1. In Mail.app, I created a smart folder that collected all mail addressed to [email protected] during the past 10 years (and which is not in my junk mail folder). This is the starting point of my list of “known senders” from whom I’ll continue to receive mails.
2. I exported this smart folder to a mailbox file on my Desktop
3. I then used the Mac app “eMail Extractor” to parse a list of all email addresses found in that file.
4. I then used BBEdit to clean up the list, leaving me with only a single copy of unique {domain}.{tld} entries.
5. I then created the following Sieve rule in my account at FastMail

if anyof(
    address :contains "To" "[email protected]",
    address :contains "To" "[email protected]"
  ) {
  if allof(
    not address :matches "From" "*domain1\.com",
    not address :matches "From" "*domain2\.com",
    not address :matches "From" "*domain3\.com"
  ) {
      reject "This email address no longer exists. 
      Please contact me through my blog at dafacto.com 
      to get my new email address.";
      stop;  
  }
}

This sieve triggers on any mail received on my old makalumedia.com addresses. It then checks if the sender is in my list of known senders (which in my real sieve is much longer than the above). If the sender is not in that list, it rejects the mail with a message to contact me through my blog to get my current contact information.

Since setting this up a few days ago, my spam has been reduced by probably 90%. The few that have gotten through were from senders on my known-senders list, and so I went and removed them from the list. So over time, my known-senders list will get cleaned of the few spammers who were present in the original list.

All in all, I’ve been super happy with Fastmail. Their service is well-designed, technically solid, and provides just enough geeky flexibility to do advanced stuff like the above. Well worth the money!

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