با سلام
ابتدا وارد SSH سرور شوید و اگر از فایروال CSF استفاده میکنید آن را توسط دستور csf -x غیر فعال کنید.
سپس دستورات زیر را اجرا کنید و وضعیت ارتباط سرور خود را با آن بررسی کنید.

[root@summer ~]# telnet alt1.gmail-smtp-in.l.google.com 25
Trying 64.233.163.27...
Connected to alt1.gmail-smtp-in.l.google.com.

کد:
[root@summer ~]# telnet alt1.gmail-smtp-in.l.google.com 25
Trying 64.233.163.27...
Connected to alt1.gmail-smtp-in.l.google.com.
کد:
[root@summer ~]# telnet mx1.hotmail.com 25
Trying 65.54.188.72...
Connected to mx1.hotmail.com.
کد:
[root@summer ~]# ping alt1.gmail-smtp-in.l.google.com
PING alt1.gmail-smtp-in.l.google.com (64.233.163.27) 56(84) bytes of data.
64 bytes from lj-in-f27.1e100.net (64.233.163.27): icmp_seq=1 ttl=46 time=38.6 ms
64 bytes from lj-in-f27.1e100.net (64.233.163.27): icmp_seq=2 ttl=46 time=38.9 ms
64 bytes from lj-in-f27.1e100.net (64.233.163.27): icmp_seq=3 ttl=46 time=38.6 ms
64 bytes from lj-in-f27.1e100.net (64.233.163.27): icmp_seq=4 ttl=46 time=38.4 ms
64 bytes from lj-in-f27.1e100.net (64.233.163.27): icmp_seq=5 ttl=46 time=38.6 ms
64 bytes from lj-in-f27.1e100.net (64.233.163.27): icmp_seq=6 ttl=46 time=40.0 ms
^C
--- alt1.gmail-smtp-in.l.google.com ping statistics ---
6 packets transmitted, 6 received, 0% packet loss, time 5912ms
rtt min/avg/max/mdev = 38.472/38.889/40.036/0.591 ms
کد:
[root@summer ~]# ping mx1.hotmail.com
PING mx1.hotmail.com (65.54.188.110) 56(84) bytes of data.
64 bytes from 65.54.188.110: icmp_seq=1 ttl=236 time=150 ms
64 bytes from 65.54.188.110: icmp_seq=2 ttl=236 time=150 ms
64 bytes from 65.54.188.110: icmp_seq=3 ttl=236 time=150 ms
64 bytes from 65.54.188.110: icmp_seq=4 ttl=236 time=151 ms
64 bytes from 65.54.188.110: icmp_seq=5 ttl=236 time=151 ms
64 bytes from 65.54.188.110: icmp_seq=6 ttl=236 time=150 ms
64 bytes from 65.54.188.110: icmp_seq=7 ttl=236 time=150 ms
64 bytes from 65.54.188.110: icmp_seq=8 ttl=236 time=150 ms
^C
--- mx1.hotmail.com ping statistics ---
8 packets transmitted, 8 received, 0% packet loss, time 7396ms
rtt min/avg/max/mdev = 150.571/150.900/151.213/0.169 ms
موفق و پیروز باشید.