Apple Mail message content not showing
I've an early 2011 MacBook Pro running Sierra 10.12.4 on a newly installed SSD. It performs very well and I view POP mail in my preferred Classic layout. I leave Mail only to return a short while later to find no content visible on any email in any of my multiple folders, just the headers. Switching out of Classic layout the content is visible (5 lines of it at least) but, on returning to Classic mode, the content is still missing.
I've tried the various suggestions from other postings here and elsewhere including removing the "Envelope Index" and "ExternalUpdates.storedata" files from V4/MailData, rebuilding the mailboxes etc.
Seeing that the content is visible in non-Classic mode I can’t see that Spotlight reindexing can help. The content is there but not being displayed in Classic mode.
Has anyone any other ideas?
MacBook Pro, macOS Sierra (10.12.4), Early 2011