I noted that mails from hotmail.com and office 365 are being recieved randomly late between 5minutes - couple hours. Is there any issue from hotmail side? Mail from yandex, gmail or some other servers are fine.
Take a look at your mail.log (/var/log/mail.log) to see when the email first comes in and what happens with it.
did you enabled greylistening for the recipient? you may have to update the whitelisted ips for greylistening in /etc/postgrey/whitelist_clients
I do not use greylisting. Mail log does not appear in /var/log/mail.log when client gets mail then I can see logs there. I do not use rspamd (but think of swtiching to it. Can I do it simply by selecting it in admin options?) Other mails from like gmail.com comes quickly. I event tried disabling in postfix but no change: content_filter = lmtp:[127.0.0.1]:10024 receive_override_options = no_address_mappings Totally stucked
In the mail.log you would see the first time the email arrives at your server. To switch to rspamd, see https://www.howtoforge.com/replacing-amavisd-with-rspamd-in-ispconfig/
Then there is a delay with hotmail, or maybe a misconfiguration in your system which makes it unable for them to reach you sometimes.
I found the issue. I was setting mail dns record as CNAME record. After changing it to A record from Cloudflare. Mail are coming fast. Very interesting.
