Exchange – inbound email only works from some servers

exchangeexchange-2003ssl-certificatetlswindows-server-2003

I am having a problem where inbound mail from outside only works when sent from certain hosts.

For example, when I send myself an email from my personal gmail account all is well, as the logs show:

2012-09-05 18:14:16 209.85.223.175 mail-ie0-f175.google.com SMTPSVC1
MAILSVR 192.168.1.79 0 EHLO 250 – –

2012-09-05 18:14:16 209.85.223.175 mail-ie0-f175.google.com SMTPSVC1
MAILSVR 192.168.1.79 0 STARTTLS 220 – –

2012-09-05 18:14:16 209.85.223.175 mail-ie0-f175.google.com SMTPSVC1
MAILSVR 192.168.1.79 0 STARTTLS 220 – –

2012-09-05 18:14:16 209.85.223.175 mail-ie0-f175.google.com SMTPSVC1
MAILSVR 192.168.1.79 0 EHLO 250 – –

2012-09-05 18:14:16 209.85.223.175 mail-ie0-f175.google.com SMTPSVC1
MAILSVR 192.168.1.79 0 MAIL 250 – –

2012-09-05 18:14:16 209.85.223.175 mail-ie0-f175.google.com SMTPSVC1
MAILSVR 192.168.1.79 0 RCPT 250 – –

2012-09-05 18:14:48 209.85.223.175 mail-ie0-f175.google.com SMTPSVC1
MAILSVR 192.168.1.79 0 QUIT 240 – –

However, if I sent from my personal Yahoo account, I get this response:

Sorry, we were unable to deliver your message to the following address.
<my.email@mycompany.com>: Remote host said: 530 5.7.0 Must issue a
STARTTLS command first [MAIL_FROM]

(NB: Nothing appeared in the smtp log for this message.)

Any suggestions where to start looking?

EDIT —-

I don't know if it matters, but the certificate I am using for TLS is self signed.

EDIT 2

I'm now using a real trusted ssl cert. OWA works fine now with no browser warnings. BUT I still get the same failure reply to messages from my yahoo account.

Best Answer

Remote host said: 530 5.7.0 Must issue a STARTTLS command first

Means your mail server is rejecting connections from mail servers that don't negotiate a TLS connection. Follow the instructions here to correct that (by not making TLS mandatory).

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