Email-to-Fax – Handling + and = in Return-Path

emailemail-forwardingemail-headersfaxgoogle-groups

I want to subscribe a fax number to a (private) Google Group mailing list, so each message sent to the list will arrive on the fax machine. I have tried several email-to-fax services include MaxEmail and MetroFax. The problem is that these services all authorize senders not based on the From: address but on the Return-Path of the envelope. And, every service I've tried disallows either + or = characters in that address.

However, Google Groups uses a Return-Path: of the form dan.kohn+caf_=915-331-0696=maxemailsend.com@example.com in order to track bounce addresses. Thus, I can't authorize that address for the email-to-fax service.

It seems like most transactional email services use + and = in their Return-Path: to be able to track bounces effectively. However, I can't find an email-to-fax service that accommodates this.

Things I've considered or tried:

  1. Finding an email-to-fax service that allows a Sender alias to include + and = characters (since they're both legal characters!).

  2. Forwarding to a Gmail account, which would then forward to the fax number. However, the Gmail Return-Path: includes the same invalid characters.

  3. Finding an "enterprise" email-to-fax service that would accept all email to mysecretusername@enterprisefax.com and fax it, no matter what the From: or Return-Path is set to. Know one?

  4. Using an email account with Procmail to rewrite the envelope header. However, Dreamhost has discontinued their Procmail integration.

  5. Using Mandrill to rewrite the Return-Path:, but this seems to only rewrite the domain, which is not the problem.

Anyway, I can't believe this should be so hard, and I would greatly appreciate any suggestions.

Update: Just to put a name to it, the issue is that most mailing lists use a Variable Envelope Return Path, but I can't seem to find an email-to-fax service that supports the + and = characters that VERP uses.

Best Answer

I believe Ring Central Fax will do what you want.

I actually called them up to answer this question and here's the answers I got:

  1. While their site talks about attaching things to email and faxing them, they will fax the body of an email message (apparently as a / in lieu of a coversheet)
  2. The account has an address whitelist
  3. ... but the email addresses on that whitelist can apparently have pluses, equal signs and commas in with their letters. (I'm at a 92% confidence level in this information)
  4. ... to match the whitelist they said they check the From Header for whitelist matching. I'm only about 80% confident in this part of the answer, as the "senior tech rep" on call literally seemed to have no idea what RFC 821 was, or how you find such a thing on the Internet. I was really hoping he'd transfer me to someone who knew, but no dice.

But, I think this information is correct (after also fighting with them on fax header vs email message header, which was a fun bit of translation / telephone too)

Ring Central mostly advertises its VOIP capabilities and the fax stuff is kind of hard to find, so I'm hoping you missed this in your survey of email to fax solutions.

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