Hi all
I've already had issues delivering mail to hotmail and outlook users in januari for this server.
During this period, this IP is not able to deliver e-mail to hotmail or outlook, the mail stays in queue until the ban is lifted.
The error shown is
Back in januari, microsoft support was prompt to lift the ban.
We are on SNDS and JMRP. This IP is not shown in SNDS because the volume is too low.
All domains have SPF and DKIM active, no exceptions. Most don't have DMARC yet, but it is on the roadmap.
I've removed all forwarders on our servers years ago, however there were 3 or 4 exceptions, I removed them a couple of days ago because of recent hotmail issues.
The exceptions have an external spamfilter, but this did not mean some spam would not be forwarded.
I hope the forwarders were the reason for the ban, I don't know what else could be wrong.
There is a script active that blocks the set up of a new forwarder if the destination is outside our network.
I prefer not to experience these issues again.
Also, years ago, I wrote a serverwide (captcha) script that blocks all POST requests to prevent websites being used for sending spam via contact forms.
This script causes our serverload to drastically decrease and prevents spam from being sent via websites hosted on our network.
Off course, it is not watertight, but it makes a big difference, 'no spam' is being sent via contact forms on our network.
PHP mail() is also continuously being monitored for abuse.
We have never been on a spam list, nor have our servers been used for malicious activities.
Low outgoing limits are active (250 / user). And if a limit is reached, the mail activity is promptly followed up on.
However since last week, we are blocked again for delivering e-mail to hotmail or outlook.
Microsoft support has not been able to lift the ban at all, not even one mail could be delivered, and we have been e-mailing for almost a week.
These are some snippets of their replies: (between May 8th until May 14th)
Our clients on this server have not been able to e-mail to hotmail or outlook for a week now.
I've tried to keep outlook and hotmail e-mail in queue without trying to deliver using an exim modification for 24 hours, but that did not change anything.
What can we do to circumvent this issue?
Could we set up new IP and route e-mail over this new IP?
Or does anyone have another idea?
Best regards and thank you for your time
Dries
I've already had issues delivering mail to hotmail and outlook users in januari for this server.
During this period, this IP is not able to deliver e-mail to hotmail or outlook, the mail stays in queue until the ban is lifted.
The error shown is
Code:
2026-05-14 17:49:33 1wN9t2-00000002BQv-3hr9 H=hotmail-com.olc.protection.outlook.com [52.101.73.17]: SMTP error from remote mail server after pipelined MAIL FROM:<[email protected]> SIZE=4169: 451 4.7.650 The mail server [999.999.999.999] has been temporarily rate limited due to IP reputation. For e-mail delivery information, see https://aka.ms/postmaster (S775) [Name=Protocol Filter Agent][AGT=PFA][MxId=11BD5B61254CB1FC] [AMS0EPF0000019C.eurprd05.prod.outlook.com 2026-05-14T15:49:33.598Z 08DEADB0994CCD76]We are on SNDS and JMRP. This IP is not shown in SNDS because the volume is too low.
All domains have SPF and DKIM active, no exceptions. Most don't have DMARC yet, but it is on the roadmap.
I've removed all forwarders on our servers years ago, however there were 3 or 4 exceptions, I removed them a couple of days ago because of recent hotmail issues.
The exceptions have an external spamfilter, but this did not mean some spam would not be forwarded.
I hope the forwarders were the reason for the ban, I don't know what else could be wrong.
There is a script active that blocks the set up of a new forwarder if the destination is outside our network.
I prefer not to experience these issues again.
Also, years ago, I wrote a serverwide (captcha) script that blocks all POST requests to prevent websites being used for sending spam via contact forms.
This script causes our serverload to drastically decrease and prevents spam from being sent via websites hosted on our network.
Off course, it is not watertight, but it makes a big difference, 'no spam' is being sent via contact forms on our network.
PHP mail() is also continuously being monitored for abuse.
We have never been on a spam list, nor have our servers been used for malicious activities.
Low outgoing limits are active (250 / user). And if a limit is reached, the mail activity is promptly followed up on.
However since last week, we are blocked again for delivering e-mail to hotmail or outlook.
Microsoft support has not been able to lift the ban at all, not even one mail could be delivered, and we have been e-mailing for almost a week.
These are some snippets of their replies: (between May 8th until May 14th)
Our clients on this server have not been able to e-mail to hotmail or outlook for a week now.
I've tried to keep outlook and hotmail e-mail in queue without trying to deliver using an exim modification for 24 hours, but that did not change anything.
What can we do to circumvent this issue?
Could we set up new IP and route e-mail over this new IP?
Or does anyone have another idea?
Best regards and thank you for your time
Dries
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