Delayed Email from Microsoft Services

My OX in UCS is doing fine. No problem but email from Microsoft domain (,, is not coming in time. It is taking more than a day to reach my server. Where email from other domain is coming instantly. What should I do?

Thanks in advance.

You’ll have to read the mail log: /var/log/mail.log
When you send an email from a test account at a Microsoft, it shouldn’t take long, for their mail server to contact your server. If there is no connection for a long time, the problem is on their side, and you’ll have to contact their support.

If there is a contact, but your server rejects it temporarily, then greylisting is activated (on by default). Greylisting stalls not-well-behaving mail servers. That is an important spam filter technique. Greylisting is activated if the UCR variable mail/postfix/greylisting is enabled.

To enable popular mail providers to bypass that check, see that the UCR variable mail/postfix/greylisting/client/whitelist contains /etc/postgrey/whitelist_clients.local and then add their mail servers to it. To catch all their server, use the domain. For Microsoft mail that is

so I should put the domain in comma seperated value in whitelist_clients.local file like
*,, ?

One server per line.
As Microsoft uses multiple servers, the complete domain catches all. The servers have FQDNs like,, etc.
So use on a single line and others as well. For example:
1 Like

After adding the record should I restart any service?

Yes, Postgrey ( must be restarted:
systemctl restart postgrey.service

Still email is delayed. Should I disable grey listing?

Are you sure greylisting is the reason? have you tried sending a mail from microsoft and observed your mail.log? How long does it take from sending the mail until the first connection from a MS mail server in mail.log?

which part should I look? Lots of log here in mail.log

Nov 26 23:54:01 ds postfix/smtpd[7765]: NOQUEUE: reject: RCPT from[]: 450 4.2.0 Recipient address rejected: Greylisted, see; proto=ESMTP helo=<>

It is causing by greylisting. Can you please show me a way to white list the whole domain?

As I wrote above, you should whitelist the SMTP client machine ( in a file listed in the UCR variable mail/postfix/greylisting/client/whitelist. Because MS uses a lot of servers you should whitelist their complete domain by putting on a single line in the file.

I have disabled the service as I am using Kaspersky email security. Now it is fantastic. But I need to know how to set UCR values for SMTP.

Please be more specific.

<<<how to do this? I have put the entries on that .local file.

Please make sure the file is listed in the UCRV:
ucr get mail/postfix/greylisting/client/whitelist

If it is, it should be in the command in the file /etc/default/postgrey and thus also when you look at the process:

$ ps xa | grep postgrey
29725 ?        Ss     0:00 postgrey --pidfile=/var/run/ --daemonize --inet=10023 
  --delay=300 --max-age=35 
  --retry-window=48h --auto-whitelist-clients=5 --lookup-by-host --privacy