Hi,
I'm having similar problems but that didn't solved it unfortunately.
The console log showed these lines before applying the solution when I tried to send a pdf file by choosing Share -> Mail from finder:
03.02.2016 17:52:04,402 ShareMail[618]: plug-in sdk "com.apple.share-services" not registered
03.02.2016 17:52:04,402 Finder[435]: plugin com.apple.share.Mail.compose interrupted
03.02.2016 17:52:04,403 Finder[435]: Hub connection error Error Domain=NSCocoaErrorDomain Code=4097 "connection to service named com.apple.share.Mail.compose" UserInfo={NSDebugDescription=connection to service named com.apple.share.Mail.compose}
03.02.2016 17:52:04,403 Finder[435]: --error: [ShareKit] error in -[NSExtension beginExtensionRequestWithInputItems:completion: Error Domain=NSCocoaErrorDomain Code=4097 "connection to service named com.apple.share.Mail.compose" UserInfo={NSDebugDescription=connection to service named com.apple.share.Mail.compose}
03.02.2016 17:52:04,428 ReportCrash[620]: Unable to find containing app bundle for /System/Library/PrivateFrameworks/ShareKit.framework/Versions/A/PlugIns/ShareMa il.appex/Contents/MacOS/ShareMail. Will not read AppStore receipt
03.02.2016 17:52:09,084 syncdefaultsd[622]: accountsd has been removed from syncing apps.
03.02.2016 17:52:25,481 pkd[442]: enabling pid=435 for plug-in com.apple.share.Mail.compose(1.0) C28F8CAA-6745-4859-9CC4-0158C3616242 /System/Library/PrivateFrameworks/ShareKit.framework/Versions/A/PlugIns/ShareMa il.appex
then tried your solution in terminal:
MacBookPro-FF:~ fechner$ /System/Library/Frameworks/CoreServices.framework/Versions/A/Frameworks/LaunchS ervices.framework/Versions/A/Support/lsregister -kill -seed
...
lsregister: registered plugin /System/Library/PrivateFrameworks/ShareKit.framework/PlugIns/ShareMail.appex
...
but at the same time my console log showed these:
...
03.02.2016 18:15:51,620 pkd[442]: plug-in sdk "com.apple.share-services" not registered
...
I'm running OS X 10.11.3 (15D21) on a MacBookPro 11,5 16GB RAM 500GB SSD
The system was freshly installed from scratch (no Upgrade) 10.11.2 and updated by the 10.11.3 combo updater.
I'm NOT admin as my normal every day working user (having a separate account for this for security reasons)