Icinga 2 does not send notification email

Icinga 2
1

Hi, please Icinga does not send anymore notification mail when i type

sudo tail -f /var/log/mail.log here is the error that i get:
"Sep  4 10:54:11 icinga2server postfix/error[3342044]: A618DCF10BC: to=<webmaster@xxxx.org>, relay=none, delay=170709, delays=170688/21/0/0.1, dsn=4.4.3, status=deferred (delivery temporarily suspended: Host or domain name not found. Name service error for name=smtp.office365.com
type=AAAA: Host not found, try again)"

Please i need your help, thank you.

2

Thanks for posting your issues. However, this is an issue on your Postfix’ end, which seems to have issues resolving smtp.office365.com. Thus, please try checking both your DNS configuration and your Postfix logs.

For starters, try to resolve the host manually from the same machine.