Steps how to reproduce with SeaMonkey German 2.39 final Mozilla/5.0 (Windows NT 6.1; WOW64; rv:42.0 from official download area) Gecko/20100101 Firefox/42.0 Build 20151103191810 (Classic Theme) on German WIN7 64bit: 0. Preparation: If necessary make SM default application for Mail and NEWS, Make Browser "default application when launch" create a newsgroup account for for Server "news.mozilla.org" (Port 119, no security) and subscribe for mozilla.support.seamonkey, download 5000 Headings quit SeaMonkey 1. Open this Bug report in FF and click folowing link: <nntp://news.mozilla.org/mozilla.support.seamonkey> » As expected SeaMonkey will be launched (for me always via Profile Manager) Bug: Browser Start Page will be shown instead MailNews Client. Additional Information: a) All the same with link above from Apache Open Office and IE 11 I will test with Thunderbird as default mail/news application later
I confirm this. I don't have Firefox so I used OpenOffice Writer (a MS Word clone) to follow the nntp: link given above (just paste the link in a document and control-click). User agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:47.0) Gecko/20100101 Firefox/47.0 SeaMonkey/2.44a1 The http browser window will open instead of the mail/news window. I found you can fix half of the bug in the registry. In the keys HKEY_USERS\(whatever the current user is)\Software\Classes\nntp\shell\open\command HKEY_USERS\(whatever the current user is)\Software\Classes\news\shell\open\command the default value data has "C:\(directory tree)\seamonkey.exe" -osint -mail "%1" It should be "C:\(directory tree)\seamonkey.exe" -osint -news "%1" That change will cause the mail/news window to open instead of the http browser window, I believe because the "-mail" option doesn't allow a parameter, only the "-news" option. If you use "C:\(directory tree)\seamonkey.exe" -osint -mail that will also open the mail/news window. However I cannot get the mail/news window to actually follow the newsgroup given in the link. It just goes to the Inbox.
(In reply to benl from comment #1) NEW Due to your research currently this looks like an installation (or OS integration?) problem.
This works better with English SeaMonkey 2.44a1 (X11; Linux x86_64; rv:47.0) Gecko/20100101 Firefox/47.0 Build 20160208023510 (Default Theme) on VirtualBox Ubuntu 14.04 LTS for link on this page in FF 43.0.4: After click a dialog will appear and ask me for default application, I simpy select SeaMonkey (with "remember") and SeaMonkey Email Client will open 8additionally to Browserf) with focus on correct NG. But the step before will not work for the same link target from LibreOffice 126.96.36.199. If SeaMonkey is not runnkng nothing happens