On 4 Jun 2019, at 8:23, subscription1 wrote:
telnet on the working server shoews
---
>>> telnet 203.205.219.57 25
Trying 203.205.219.57...
Connected to 203.205.219.57.
Escape character is '^]'.
220 newxmmxsza20.qq.com MX QQ Mail Server.
^]
telnet>
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On the failing server I get
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>>> telnet 203.205.219.57 25
Trying 203.205.219.57...
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I can ping 203.205.219.57 from both servers
This is a symptom of your network provider blocking port 25 outbound.
That has long been the norm for residential/recreational service and in
recent years it has expanded to the low-end hosting market (including
Amazon and OVH,) where it is now common for hosting providers to block
port 25 outbound by default and either provide an authenticated relay
service (e.g. Amazon SES) or to unblock the port by customer request.
Making the issue more complex, some providers have implemented port 25
blocking unevenly, so that some of their customers or networks are
unblocked despite the official practice.
--
Bill Cole
[email protected] or [email protected]
(AKA @grumpybozo and many *@billmail.scconsult.com addresses)
