[CentOS] SMTP Port 465 - Postfix

Tilman Schmidt t.schmidt at phoenixsoftware.de
Sat Mar 31 08:16:20 EDT 2012


Am 31.03.2012 13:36, schrieb Jonathan Vomacka:
> On 3/31/2012 7:11 AM, Prabhpal S. Mavi wrote:

>> But when i telnet 587, i can see 220 in response.
>> [root at jet postfix]# telnet localhost 587
>> Trying ::1...
>> Connected to localhost.
>> Escape character is '^]'.
>> 220 mail.digital-infotech.com ESMTP Postfix (2.6.6)
>>
>> But when i telnet to 465, i do not see 220 in response. is it normal?
>> [root at jet postfix]# telnet localhost 465
>> Trying ::1...
>> Connected to localhost.
>> Escape character is '^]'.

Expected behaviour. Bear in mind that 465 is the old deprecated
SMTPS (SMTP over SSL) port which just runs SMTP over an SSL session.
Postfix cannot send a greeting on that port without completing the
SSL handshake first, but Telnet doesn't speak SSL. So Postfix is
just waiting in vain for the SSL handshake.

> I thought port 465 SSL was deprecated

Correct.

> and replaced with port 587 TLS?

Not quite. It's replaced with STARTTLS which works over port 25
(SMTP) as well as 587 (MSP).

HTH
T.


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