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I've been looking for an answer to this all over the internet, and sadly I've come nowhere near one.

Today I decided to write a SMTP server for sending/recieving emails from my RPi. I wanted to do it from scratch, so switching to Postfix is not an option. I've wrote my code on Java and all the connections are handled with sockets.

My server works like -as I understood- most SMTP servers work: - Email sender connets to my server on port 25. - I say "220 Hello, welcome to my server" - They then reply HELO or EHLO and so the communication goes on.

This has worked great so far with GMail, some anonymous email sending websites, mail.com, etc, but I can't make it work with Hotmail and Yahoo. They connect, I send them the "220 Hello, etc" line, but they don't reply HELO nor EHLO nor anything at all.

Yahoo has been trying to connect for a while now, but they don't reply anything at all. Neither does, again, Hotmail.

Do you know if they work in some special way, if I am messing something up with the protocol, or what could be happening?

Thank you very much.

EDIT Some other things: - I'm using a No-ip address. - I'm listening to ports 25, 465 and 587, and all of them have been opened in my router.

Lartu
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  • Since Yahoo etc are known to work with other servers there must be something wrong with your server. But since you don't provide any kind of code, packet dump or similar there is no way to find out what the real problem might be. Therefore I propose to close this question. – Steffen Ullrich Mar 11 '16 at 07:53

1 Answers1

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Make sure your lines end with \r\n and not just \n.

jstedfast
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