Bug 146627 - Mail submission agent on port 587 ignored by Mailtransport
Summary: Mail submission agent on port 587 ignored by Mailtransport
Status: RESOLVED UNMAINTAINED
Alias: None
Product: kdepimlibs
Classification: Applications
Component: mailtransport (show other bugs)
Version: 4.2
Platform: unspecified Linux
: NOR wishlist
Target Milestone: ---
Assignee: kdepim bugs
URL:
Keywords:
Depends on:
Blocks:
 
Reported: 2007-06-10 11:05 UTC by Zbigniew Luszpinski
Modified: 2020-10-19 23:09 UTC (History)
2 users (show)

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Description Zbigniew Luszpinski 2007-06-10 11:05:20 UTC
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.
Comment 1 Malte S. Stretz 2008-10-05 16:35:28 UTC
Port 587 is now even recommended by RFC 5321.  I think the autodetection algorithm outlined above is the perfect way to go.
Comment 2 Tom Albers 2009-02-18 18:46:10 UTC
Ok, I'll read up and add support for it, hopefully before 4.3.0. Thanks for the excellent report.
Comment 3 Tom Albers 2009-05-31 20:37:18 UTC
This addition will clutter the code to much, it needs large hacks to get it to work. I will try to rewrite the class to make this possible later on.
Comment 4 Sandro Knauß 2020-10-19 23:09:20 UTC
Thank you for taking the time to file a bug report.

The compontent kdepimlibs don't exist anymore since 2011. It was splitted into several parts some moved to Frameworks the other are still under de KDE PIM umbrella. 

The entire code base went through significant changes. We ported the source code in meanwhile  to Qt5 and KF5. It is unlikely that these bugs are still valid in KMail2.

We welcome you to try out the new 20.08 release and give your feedback.