Resolved hotmail rejects mail 550 SC-001

[geehaa]

i can send email to every mail server in the milkyway, (and even to the andromeda system) but just not to hotmail servers.

550 SC-001 Mail rejected by Outlook.com for policy reasons. Reasons for rejection may be related to content with spam-like characteristics or IP/domain reputation. If you are not an email/network admin please contact your Email/Internet Service Provider for help.

mxtoolbox reports only one problem:
Reverse DNS is not a Valid Hostname

but it is perfectly valid.

i know this issue has been reported several times here but i cant find a satisfactory solution.

what should be done in this case?

 

[UFHH01]

Hi geehaa,

Mail rejected by Outlook.com for policy reasons

Your described issue has got nothing to do with Plesk and is related to "Outlook.com policy reasons".

You got additional hints here in your message:

Reasons for rejection may be related to content with spam-like characteristics or IP/domain reputation

Pls. check for example:

=> Microsoft Community
=> How to Remove Your IP from the Hotmail Blacklist
=> Troubleshooting​

 

[mr-wolf]

mxtoolbox reports only one problem:
Reverse DNS is not a Valid Hostname

but it is perfectly valid.

To be able to send to hotmail.com, live.com & outlook.com you need to be almost impeccable.

I don't think your server's PTR is valid if mxtoolbox says it's not.
As you're not saying what it is I can't tell you what's wrong with it.

If you are trying to run a mail server with a PTR that doesn't match your forward DNS you are a long way from being that.

Some beginner stuff regarding IP/DNS for a mail server

• DNS should be a sub-domain (not a sub- sub- domain), that means only 2 embedded dots
• DNS should not contain an IP
• PTR should match forward DNS (this will proof you have some authority regarding your IP)
• HELO should match DNS
• As an extra put this SPF on your HELO: a -all

Like @UFHH01 mentioned, there's much more to it.

When I setup a new mailserver on a new machine I had my mail rejected by hotmail.com even though everything was top notch. It took much correspondence with Microsoft to get it whitelisted.
They insisted it had been sending spam, which was not possible as it was a new server.
They couldn't, of course, give me any proof of that.

For a month I was relaying mail to Microsoft through another server which was fine. After that I was able to send directly..

I think the previous owner of that IP built up some reputation. It's hard to get rid of that.