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My SMTP server is located in central Europe and I can connect to it just fine. However, a user from Japan was not able to connect to my server using Thunderbird.
I set it up together with him and used the exactly same options to rule out any mistakes.
Why is that so?
MechMK1
Posted 2014-03-04T17:56:33.790
Reputation: 507
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It it possible that the Japanese users ISP is blocking outbound connections from end users on port 25 to force mail through their mail server and thus reduce spam. Have you tried opening an alternative port (587 - Submission) is usually used for the purpose of sending email to an SMTP server, or port 465 for sending over SSL.
In my part of the world, occasionally port 26 is used to perform the same as port 25, save as to get round the largest regional ISP's block.
davidgo
Posted 2014-03-04T17:56:33.790
Reputation: 49 152
I'll check that! – MechMK1 – 2014-03-05T07:16:03.313
Does your smtp server use public blacklists? Your user might be in a blacklisted block. – GnP – 2014-03-04T18:01:12.150
No, the smtp server only checks for valid authentification. – MechMK1 – 2014-03-04T18:19:04.523
What troubleshooting have you done? Have you checked name resolution from the client? Trace route from the client? Telnet from the client? Etc., etc. – joeqwerty – 2014-03-04T18:37:36.303