Bug 146627

Version:           1.9.7 (using KDE 3.5.7, compiled sources)
Compiler:          gcc version 3.4.6
OS:                Linux (i686) release 2.6.21.4

KMail has no support for "Mail submission agent" (MSA) autodetection. Typing in 587 port in smtp manually however allows me to use MSA.
http://en.wikipedia.org/wiki/Mail_submission_agent
http://www.ietf.org/rfc/rfc2476.txt

MSA should be preferred way of sending mail from KMail. That is why I think autodetection should set it by default when available instead of ordinary smtp on port 25.

The autodetection of MSA is the same like for ordinary smtp on port 25. In case of MSA port 587 should be checked. The smtp protocol and features exposed to mail client are the same for 25 and 587 port.

Now when I setup new smtp account I do following steps in KMail:
1. Replace port 25 with 587 then click autodetect.
2. If smtp server has nothing on port 587 I fallback to 25.
The autodetection button works great on both 587 and 25. However it should prefer 587 than 25.

Improved autodetection mechanism may look like this:
1. check for TLS on 587 (STARTTLS)
2. check for SSL on 465
3. check for TLS on 25  (STARTTLS)
4. check for smtp on port 587
5. fallback to old smtp on 25 port

2 of my 5 mail service providers already use port 587. After forcing KMail to use port 587 for smtp I can use the same set of features I used to have on port 25 like TLS or advanced authentication. I will be forcing the rest of my mail service providers to open 587 port for mail submission so I could permanently close port 25 on home router to block mail threats and junk.

The advantages of MSA:
*smtp on port 25 is designed for server-server mail exchange - mail header can not be changed. Smtp on port 587 is designed to mail client-server mail submission. MSA can correct many things in header of mail to protect against forgery and block spam or interact with mail client.
*some ISP and MSP block port 25 to avoid spreading viruses and spam.