I’m looking for an email service that issues email addresses with an onion variant. E.g. so users can send a message with headers like this:
From: replyIfYouCan@hi3ftg6fgasaquw6c3itzif4lc2upj5fanccoctd5p7xrgrsq7wjnoqd.onion
To: someoneElse@clearnet_addy.com
I wonder if any servers in the onionmail.info pool of providers can do this. Many of them have VMAT, which converts onion email addresses to clearnet addresses (not what I want). The docs are vague. They say how to enable VMAT (which is enabled by default anyway), and neglect to mention how to disable VMAT. Is it even possible to disable VMAT? Or is there a server which does not implement VMAT, which would send msgs to clearnet users that have onion FROM addresses?
Sure it is. I can theoretically¹ do it myself with my mail server. If you use a mail client like (neo)mutt, you can literally free type whatever you want to put in the FROM field. IIRC, this contradicts no RFCs so long as there is a syntactically valid email address.
Ever get an email with a bogus address like “noreply@corporation.xyz”? It’s essentially the same. Not all e-mail addresses in the FROM field go to valid inboxes – nor are they required to.
footnote 1
The reason I say “theoretically” is that some exceptional SMTP servers check that the domain portion of the FROM email passes an MX lookup or that the DNS lookup matches the sending server. It’s a rare configuration. I have no domain name so my mail server always sends msgs with a “spoofed” email address (which is often valid but not related to my IP). I also write in completely bogus email addresses in some cases where no reply is needed. Very few servers reject on that basis. The other complication is that many mail services disallow outbound messages with a different address than what they assigned to a user.
You’re talking about using the FROM address for replying purposes. The point of having this option is to make replies very difficult, but still possible.
Mail servers can be configured to handle onion addresses. I’ve configured postfix to do that. But indeed most servers are not configured to handle onions, which any users who make use of the feature would need to be aware of. It’s a useful scenario because it can be used to force recipients out of Google’s and Microsoft’s walled gardens, and give them incentive to join the free world away from surveillance advertisers, for example. They must join an onion-capable email service if they want to reply.
Your information is way out of date. Almost every server tries to resolve the sending fqdn, if only to check spf and dkim records. The sending domain not existing will usually leave your messages in spam or outright blocked.
If you monitor IRC channels on email servers, you’ll find there are plenty of email admins unwilling to even go through the dkim and dmarc hoops. An fqdn check not on the sending server but on the FROM field of a msg is over-zealously above and beyond dkim and dmarc. I’m quite fine with not reaching these fringe servers. I can always decide from the bounce msg whether it’s worth my effort to dignify their excessive hoops with a transmission to their persnickety liking.
Oh yeah, fringe servers such as checks notes Gmail and Microsoft. Let us know how that goes!
Gmail doesn’t care what the FROM field address is. It can be entirely unrelated to the sending server and can be complete gibberish nonsense. MS did not care either back when MS did not consider dynamic IPs blacklisted. Now that MS wholly rejects dynamic IPs I’m not interested in retesting that anyway.