While I was looking for a clue why I the mails to my Hotmail address were blocked, I found something dealing with CAN-SPAM Act. I think it did not appear previously here, please let me know if this is the case !
In some words : to comply with this Act, the headers have to contain something like:
I’ve understood that this was just for mailing-lists, but I suspect that Microsoft checks the existence of this header for all mails arriving to their servers.
Is there a way to include such an option in Mail-in-a-Box, without breaking all the fantastic work already done ? I think it is “just” a configuration in Postfix (refer to : List Unsubscribe Header: Why and How to Use | Mailtrap Blog) but I did not succeed in making it work on my MiaB server.
… just a precision : I read this post Guide - How to unblock from Microsoft / Hotmail / Live
In my case, the answers I get are : Your IP (xxxx.yyyy.zzzz.aaaa/32) was blocked by Outlook.com because Hotmail customers have reported email from this IP as unwanted. One possible explanation for this is the automatic forwarding of unfiltered inbound messages, including unwanted messages, to Sign in to Outlook addresses.
In SNDS, I can read the status “Blocked due to user complaints or other evidence of spamming” - even if I’m the only one who received mails from my MiaB server. I tried several times (since the first time 6 weeks ago) to contact the Outlook Deliverability Support Team, but it has always ended with something like :
As previously stated, your IP(xxxx.yyyy.zzzz.aaaa) do not qualify for mitigation at this time. I do apologize, but I am unable to provide any details about this situation since we do not have the liberty to discuss the nature of the block.
It rather looks like Microsoft just block all addresses by default, and you have to jump through their hoops to unblock. I’ve used a couple of unrelated addresses for my MIAB server, none appeared on any of the normal blacklists. But always, Microsoft send a you-were-blocked bounce and I’ve had to follow their I’m-not-a-spammer procedure. Annoying but it’s simple enough and has worked well for me.
(My server is plain vanilla MIAB but running on a little server at home, with a fixed IP address. And it doesn’t seem to matter if you have received email from Microsoft or the MIAB address is in an Outlook address book - it’s looks like it’s always new-IP-you’re-blocked.)
I’ve had this non-answer from Microsoft as well, but one indication I had was that my IP was in the same netblock as one which had been spamming, so they simply blocked the entire netblock. That’s pretty obtuse and unhelpful of them, but probably the kind of approach that also explains why my xbox.com subscription emails (in fact the only emails) I get in a brand new Outlook mailbox go straight to spam – they don’t even trust themselves!