":MD:DeviceId" = 16777220;
   ":MD:kMDItemPath" = "/Users/flo/Library/Caches/Metadata/Thunderbird/ImapMail/sslmailpool.ispgateway.de/INBOX.mozmsgs/V6060829.z899.p28.X0.B0%40mx14.exklusivvorteile24.com.mozeml";
   "_kMDItemContentChangeDate" = "2017-09-28 20:34:19 +0000";
   "_kMDItemCreationDate" = "2017-09-28 20:34:19 +0000";
   "_kMDItemCreatorCode" = 0;
   "_kMDItemFileName" = "V6060829.z899.p28.X0.B0%40mx14.exklusivvorteile24.com.mozeml";
   "_kMDItemFinderFlags" = 0;
   "_kMDItemFinderLabel" = 0;
   "_kMDItemIsExtensionHidden" = 0;
   "_kMDItemOwnerGroupID" = 20;
   "_kMDItemOwnerUserID" = 501;
   "_kMDItemStaticInterestScore" = 1;
   "_kMDItemTypeCode" = 0;
   "com_apple_metadata_modtime" = "528323659.5583048";
   kMDItemContentCreationDate = "2017-09-28 20:34:19 +0000";
   kMDItemContentModificationDate = "2017-09-28 20:34:19 +0000";
   kMDItemContentType = "com.mozilla.thunderbird.mozeml";
   kMDItemContentTypeTree =     (
       "public.item",
       "public.content",
       "public.data",
       "public.email-message",
       "public.message",
       "com.mozilla.thunderbird.mozeml"
   );
   kMDItemDateAdded = "2017-09-28 20:34:19 +0000";
   kMDItemDisplayName =     {
       "" = "V6060829.z899.p28.X0.B0%40mx14.exklusivvorteile24.com.mozeml";
   };
   kMDItemKind =     {
       "" = "Thunderbird Mail Message";
   };
   kMDItemLogicalSize = 3059;
   kMDItemPhysicalSize = 4096;

Hello, the mail search via spotlight is not working correctly. When entering a subject or a sender, nothing relevant shows. Indexing is enabled in Thunderbird and many many .mozeml files with the necessary contents are created (mail subject, contents, etc.). However, the spotlight indexer seems not to be able to read it correctly. Here is an example output of mdinput: mdimport -d3 Library/Caches/Metadata/Thunderbird/ImapMail/sslmailpool.ispgateway.de/INBOX.mozmsgs/V6060829.z899.p28.X0.B0%40mx14.exklusivvorteile24.com.mozeml 2017-09-28 22:37:27.326 mdimport[674:19999] Cannot find function pointer MetadataImporterPluginFactory for factory 37401ADE-1058-42DB-BBE5-F2AAB9D7C13E in CFBundle/CFPlugIn 0x7f8584f0fd80 </Applications/Thunderbird.app/Contents/Library/Spotlight/thunderbird.mdimporter> (bundle, loaded) 2017-09-28 22:37:27.327 mdimport[674:19999] Imported '/Users/flo/Library/Caches/Metadata/Thunderbird/ImapMail/sslmailpool.ispgateway.de/INBOX.mozmsgs/V6060829.z899.p28.X0.B0%40mx14.exklusivvorteile24.com.mozeml' of type 'com.mozilla.thunderbird.mozeml' with plugIn /Applications/Thunderbird.app/Contents/Library/Spotlight/thunderbird.mdimporter. 2017-09-28 22:37:27.328 mdimport[674:19999] Attributes: { ":MD:DeviceId" = 16777220; ":MD:kMDItemPath" = "/Users/flo/Library/Caches/Metadata/Thunderbird/ImapMail/sslmailpool.ispgateway.de/INBOX.mozmsgs/V6060829.z899.p28.X0.B0%40mx14.exklusivvorteile24.com.mozeml"; "_kMDItemContentChangeDate" = "2017-09-28 20:34:19 +0000"; "_kMDItemCreationDate" = "2017-09-28 20:34:19 +0000"; "_kMDItemCreatorCode" = 0; "_kMDItemFileName" = "V6060829.z899.p28.X0.B0%40mx14.exklusivvorteile24.com.mozeml"; "_kMDItemFinderFlags" = 0; "_kMDItemFinderLabel" = 0; "_kMDItemIsExtensionHidden" = 0; "_kMDItemOwnerGroupID" = 20; "_kMDItemOwnerUserID" = 501; "_kMDItemStaticInterestScore" = 1; "_kMDItemTypeCode" = 0; "com_apple_metadata_modtime" = "528323659.5583048"; kMDItemContentCreationDate = "2017-09-28 20:34:19 +0000"; kMDItemContentModificationDate = "2017-09-28 20:34:19 +0000"; kMDItemContentType = "com.mozilla.thunderbird.mozeml"; kMDItemContentTypeTree = ( "public.item", "public.content", "public.data", "public.email-message", "public.message", "com.mozilla.thunderbird.mozeml" ); kMDItemDateAdded = "2017-09-28 20:34:19 +0000"; kMDItemDisplayName = { "" = "V6060829.z899.p28.X0.B0%40mx14.exklusivvorteile24.com.mozeml"; }; kMDItemKind = { "" = "Thunderbird Mail Message"; }; kMDItemLogicalSize = 3059; kMDItemPhysicalSize = 4096; } This happens for Thunderbird 52.3.0 and 56.0b3 under macOS High Sierra. If you need any further information, feel free to ask. Best regards, Florian