Emails to members with hotmail accounts soft bouncing

[cwe]

Within the last couple of weeks, my forum members that registered accounts using @hotmail.com email addresses are having issues receiving emails from my forum. I checked my email bounce log in the admin control panel and see numerous 'soft bounce' logs for these @hotmail.com addresses.

Looking at the details of the log entries, all the @hotmail.com addresses show the same message:

 ----- The following addresses had permanent fatal errors -----
< <useraddr>@hotmail.com>
    (reason: 550 5.7.1 Service unavailable, Client host [<email server IP address>] blocked using Spamhaus. To request removal...w.spamhaus.org/query/ip/<email server IP address> (AS3130). [SN1NAM01FT011.eop-nam01.prod.protection.outlook.com])

   ----- Transcript of session follows -----
... while talking to hotmail-com.olc.protection.outlook.com.:
>>> MAIL From:<cwebounced+83d4cbfc+<useraddr>=hotmail.com@coping-with-epilepsy.com> SIZE=8368
<<< 550 5.7.1 Service unavailable, Client host [<email server IP address>] blocked using Spamhaus. To request removal from this list see https://www.spamhaus.org/query/ip/<email server IP address> (AS3130). [SN1NAM01FT011.eop-nam01.prod.protection.outlook.com]
554 5.0.0 Service unavailable

I have checked https://www.spamhaus.org/query/ip/<email server IP address> several times across several days and I always get the same result:

<email server IP address> has no issues
In the last month we have observed 6 listings.

<email server IP address> has been detected 6 times in the last month. It has been removed 0 times.

If my email server's IP address has no issues, why is spamhaus blocking my emails? Has anyone here ever experienced this before? How did you fix it?

 

[motowebmaster]

Looks like you've checked spamhaus already, but may be worthwhile to check using this:

https://check.spamhaus.org/

If I were allowing hotmail addresses, this is one item I'd use.