Carlos E. R. wrote:
On 21/09/2018 13.48, James Knott wrote:
On 09/21/2018 01:38 PM, Per Jessen wrote:
Google (gmail) I suspect does not allow talking on :25 without encryption, or the email can be easily read on transit. No, Google does not require TLS.
Actually, it does. I just tried setting my smtp server to port 25 & no security. I got this error message:
An error occurred while sending mail. The mail server responded: 5.7.0 Must issue a STARTTLS command first. i26-v6sm9327158ioj.33 - gsmtp. Please verify that your email address is correct in your account settings and try again.
So, it would appear STARTTLS is mandatory, so that encryption can be used. I also seem to recall Google saying SSL/TLS would be required to connect to their servers. They are heavily promoting encryption in general, even preferring https sites to http in web searches.
Yep :-)
Okay, let me post some output so you can both see:
per@io64:~/Documents> dig gmail.com mx
; <<>> DiG 9.4.1-P1 <<>> gmail.com mx
;; global options: printcmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 43936
;; flags: qr rd ra; QUERY: 1, ANSWER: 5, AUTHORITY: 4, ADDITIONAL: 8
;; QUESTION SECTION:
;gmail.com. IN MX
;; ANSWER SECTION:
gmail.com. 3600 IN MX 5 gmail-smtp-in.l.google.com.
gmail.com. 3600 IN MX 10 alt1.gmail-smtp-in.l.google.com.
gmail.com. 3600 IN MX 20 alt2.gmail-smtp-in.l.google.com.
gmail.com. 3600 IN MX 30 alt3.gmail-smtp-in.l.google.com.
gmail.com. 3600 IN MX 40 alt4.gmail-smtp-in.l.google.com.
per@io64:~/Documents> host gmail-smtp-in.l.google.com.
gmail-smtp-in.l.google.com has address 173.194.79.27
gmail-smtp-in.l.google.com has IPv6 address 2a00:1450:4013:c05::1a
per@io64:~/Documents> telnet 173.194.79.27 25
Trying 173.194.79.27...
Connected to 173.194.79.27.
Escape character is '^]'.
220 mx.google.com ESMTP x2-v6si4659966edq.366 - gsmtp
EHLO klop99.example.com
250-mx.google.com at your service, [185.85.248.1]
250-SIZE 157286400
250-8BITMIME
250-STARTTLS
250-ENHANCEDSTATUSCODES
250-PIPELINING
250-CHUNKING
250 SMTPUTF8
MAIL FROM: