Q: Is there any reason at all to upgrade to El Cap? The hassles people encounter give me a strong NO answer.

I suggested that assistance can be obtained by posting here. I never mentioned that you would need to understand log files or diagnose issues yourself.

Again I will ask you please comment on what I actually said, not your interpretation of it.

SiHancox wrote:

Importing the issue back in can be a real risk I agree, but don't you consider that is reducing now a days...

In a word, no. Others have mentioned reasons for this but it all comes down to the data structures being ever more complex & interrelated, which means it is nearly impossible even for very knowledgable users to be sure what is safe to restore or what will happen if they fail to restore something they should.

It is very easy to end up spending much more time trying to sort all this out than just trying to identify & fix the problem that tempted you to do the clean install to begin with.

If you follow these discussions for long you should notice that the more experienced users regularly suggest the same short list of troubleshooting steps designed to help pin down & eliminate most issues. What may not be that obvious is they are recommended not just because they have proven to be effective, but also because they don't take very long & are easy for almost any user to understand how to do.

That's really what this is all about: why waste time trying something complicated & prone to error that may not fix the issue -- & could cause other ones if not done correctly -- when you could benefit from the collectively experience of a group of users who have already "been there & done that" enough to know what works well & what does not?

Let Apple look after syncing mail, contacts, calendars, reminders, safari and notes for convenience and not really bothered if anyone else saw them, they would probably be bored stiff anyhow

Not in this life; stealing private information isn't just to read and be bored - the info is sold online. See this article here:

http://www.philly.com/philly/business/comcast/20151111_Batch_of_Comcast_customer s_faced_online_account_threat.html

   "...but if you asked me to dig deep into the system, read and understand log files to diagnose issues I would simply be lost"

Again, I was not quoting you or implying you had asked me (the but if should have given you a clue to that), I was simply trying to express why I approach things the way I do - I really am getting the feeling you are now trying to pick on every word.

Thank you, the increasing complexity of data structures is something I had not realised and I am now beginning to see why you and the other contributors approach issues in a different way.

Does this complex and interrelated data structure come in to play and cause issues if you just bring your data in through the Apps import function, in other words you have a clean system and all you have done is sign in to various Apple accounts, you then open Mail and import your messages from previously exported mboxs.

Can see how things could get messed up if you try and do same through the Finder but would not the import function look after this data complexity issue, could you please expand further.

Yes, I did realise that this hacked data is moneytorised, but what is contained in my Contacts can easily be obtained through other means, the data taken from TalkTalk details name, address, phone number, email address, bank sort and account number but no complete credite card numbers or passwords (supposedly) - again all these could be obtained by other means.

Do not even write anything in an email or text that I would not mind anyone seeing because of how things are progressing in the UK regarding privacy.

Banks in the UK have tightened up on procedures and they now watch more carefully for unusual account activity and if they consider one is in progress you are contact to confirm if all is ok - reassuring in a way.

The immediate issue is with spam phone calls at the present, they have obviously obtained some of your data (purchased no doubt) and try to gain access to the other by quoting what they have and pretending to be from the company concerned.

SiHancox wrote:

Does this complex and interrelated data structure come in to play and cause issues if you just bring your data in through the Apps import function, in other words you have a clean system and all you have done is sign in to various Apple accounts, you then open Mail and import your messages from previously exported mboxs.

I wasn't kidding when I said it is almost impossible to know what is safe to restore from a backup. Your exported mboxs should be safe to import, but that doesn't mean if there was a problem with the original Mail.app mailbox, or with Mail.app itself, the exported mbox will be useable or not cause problems if you import it into your newly cleaned system.

The nerdy details, if you are interested: If you double-click on one of your exported mboxs in Finder, you might be surprised to see that it is actually a folder, & there are no individual email messages in it. Instead, there is a file named "mbox" & one named "table_of_contents." As explained here, the "mbox" file is one long plain text file containing the email messages, one after the other. As explained in the "Family" section of that article, it depends on a very specific & somewhat fragile structure to identify the beginning of each individual email. If that structure isn't maintained during export, or the "table_of_contents" file is corrupted, your import won't be "clean," & it could cause problems when you try to open it in Mail.

Indeed, it may stop Mail from fully loading, or it may load and the take an indeterminate and possibly infinite amount of time to load the mail.

One of my favorites

Thanks (and to Csound1 as well), if these mbox's can't be relied upon and could actually lead to unusual behaviour (and there is know easy way to confirm that they are ok prior to use) would not the emix individual ones be a better bet, all be it you may have hundreds and you have to go looking under your Library/Mail/V3/.... folders.

I have noticed that Quick Look will show the contents of these files without opening - would you consider that viewing process with QL as proof the file itself is sound so safe to use. Saying that, I have never used emix files to bring back data into mail before so would need to look that up, but it would justify why I continually backup my Library folder as well as export data through the Apps.

Thanks again for your time.

SiHancox wrote:

... would not the emix individual ones be a better bet, all be it you may have hundreds and you have to go looking under your Library/Mail/V3/.... folders.

I think you have answered your own question. It is just a bet & a very time consuming one at that.

Beyond that, you probably have noticed there are other files in  the V3 subfolders, including a variety of .plist & other files storing metadata about the messages, the state of the various mailboxes, & so on. There is no guarantee that all of that will be updated as it should be if you just drop a bunch of emix files into ~/Library/Mail/V3 folders, even if you take the time to laboriously reconstruct the V3 folder hierarchy manually & manage to get every emix file into the proper place.

IOW, you may well encounter Csound1's "favorite" behavior. If you do, you are back to square one, with not much of a clue about what went wrong or the best way to fix it.

Thank you for taking the time to explain, I am now appreciating it is not as straight forward as I first thought, using these mbox's as an example and seeing how mail structures it's data system (first time I have dug that deep) I now realise the dangers a little more clearly, and what others have been saying.

Mr. Galt,

My query is perhaps slightly off topic but you mentioned, "When you satisfy yourself that El Capitan works for you, then "clone" the external disk's contents to your internal one" . I would be grateful if you could advise the recommended method for "cloning".

Download and install either Carbon Copy Cloner or SuyperDupper. Either of which can create a bootable clone for you.