error 10060 outbound email error

[alicnc2002]

Hi,

My server worked fine till 20 days ago which suddenly start getting this error for some emails:

DNS resolved to the following record: IP Address=67.195.204.77, Family=2, Type=1, Protocol=6
Communications Error: Socket connection to mta6.am0.yahoodns.net failed (error 10060). The host was either not contactable or it rejected your connection. Socket Family = 2; Host=67.195.204.77; Port=25

first I called my ISP, they confirmed that there is no port blocking policy.
checked logs and found out that emails are delivered on some cases. all Gmail, Hotmail, Yahoo and Zoho mail are faces same issue and did not delivered.

I checked telnet from server side, get no response from mentioned providers. checked telnet from outside of server, it works fine. checked routers, no change and no firewall blocking any port.

any suggestion?

Thanks in advance,

[Admin]

If using telnet does not connect to the server, i.e.:

telnet mta6.am0.yahoodns.net 25

then it is unlikely the mail server can send email. Does it work to our server?

telnet mailenable.com 25

Does that also fail? Then check to see if an alternate port works:

telnet mailenable.com 587

If they all fail then you may need the help of your server provider. If port 25 fails, but 587 works, then it would seem they are blocking ports.