#StackBounty: #ubuntu #debian #kvm-virtualization #telnet #proxmox Can't telnet a server from vps

Bounty: 50

i try to understand why i can’t telnet this server from any of my VPSs.
Well this ip is for a mail server i don’t own but our emails are not received by this server. when i checked the log i saw this error:

554 5.7.1 You are not allowed to connect.
Connection closed by foreign host.

I thought i’m in black list so i tried to telnet to that server from all my VPSs (7 VPSs) and always get the same error.

telnet 25
Connected to
Escape character is '^]'.
554 5.7.1 You are not allowed to connect.

But when i try from a dedicate server i can telnet.

I have contacted the server admin but didn’t get any response. I still don’t see any reason for them to block my IP address. we just installed the server and it’s used for regular emails only.

Please help me

My VPSs run debian/ubuntu/centos and all created created by proxmox

Get this bounty!!!