Thank you for the answer !
Yes I did learn that Mail.app saves attachements in the Mail Downloads folder, but I do not understand - why is this action done ? Why does the system make a folder with 1Gb size (I use mail.app for like 4 months only) without asking me? One of the reasons I love MacOs - it does not litter the system as much as Windows does. And huh, here we go - the program itself saves attachements even from spam messages just because I opened them (out of curiosity) in some folder in a weird location . . .
"Are you using Time Machine, or another routine to back up your system?" Unfortunately I did not get used to Time Machine by any means, so I back-up manualy.
The program needs some place to store attachments that you open. If someone sends you a Word document, then it will need to be stored temporarily in some location so the system can have it ready if and when you decide to access it. One option is to store these along with the message itself, the other is to leave it on the server, and the last is to store them all in a central location. Mail does the latter.
This same behavior is true for any files you open in any application, be they in a Web browser, email client, or otherwise. Many programs cache files so if you browse by them it can make them available quickly without requiring you re-download them every time. The system merely downloading content in this manner will not hurt you. If you remove the corresponding email message, then the temporary items should disappear as well (eventually). If not, and they appear orphaned, then you can remove them manually without hurting anything. The system will only repopulate the items as you use it.
1) Okay, so it looks like I am starting to understand ( in this case I guess all other mail programs like MS Outlook, Windows Live, Thunderbird etc have the very same folder that automatically fills up with opened/viewed files ?)
2) Returning to my first post : If I delete this temporary folder "Mail Downloads" will the attached files remain in my mail.app ? Or in another words : are all messages AND ATTACHEMENTS stored in folder "Mail->V2"? In case this is correct, I can clean the folder Mail Downloads any time WITHOUT damaging attached files in my mail.app ? (the contect will just refill with temporary files if I view/open the attachements again)
3) "...any files you open in any application, be they in a Web browser..." from this statement I realise that there are another folders that occupy my disc space and that are to be cleaned manualy by user ? Since I use apple laptop, I have strict limitation of space even having maximum 512 gb ssd. Would you recommend cleaning these temporary folders manualy, or should I use CleanMyMac ( I heard that a user should care a lot before cleaning his Mac with 3d party apps, because it may corrupt some important files or occasionally delete them)
These programs will have their own options for caching attachments and other files.
As long as the attachments are on the server, then they will be re-downloaded when you next sync with the server. If your email accounts are IMAP accounts, then this means that if you will be able to access the attachments again as the messages simply sync with what is on the server. On the other hand, POP accounts may download the files to your system and then remove them from the server so they may not be available afterwards. You can check the type of account by going to the Mail preferences, and in the Accounts section check the type of account right under the account name (ie, Gmail IMAP is an IMAP account).
These folders aren't "to be cleaned" on any regular basis, by any means. They are there to support the program's functions, and if you remove them you will to some degree disrupt the program's functions. If there is corruption in these folders then this can slow the program down or cause other problems, in which case a cleaning of sorts may be warranted; however, if not then a cleaning is likely unnecessary.
If you are running low on space, then I would recommend you leave the system and application support files alone, and instead tackle how much user data you have on the system instead. These are things like movies, music, and pictures, with which the system does not interact.
Okay I clearly understand you position!
I use POP mail account, because it is important for me to have complete back-up copy of all messages and attachements.
Although I've attentively got acquainted with your message let me kindly re-ask the question, because the following statement seems weird to me.
Mail stores all messages, account info, notes, message folder structure in one place : "User->Library->Mail->V2" , while storing another INTERGRAL part of messages (attachements) in COMPLETELY another place : "User->Library->Containers->com.apple.mail->Data->Library->Mail downloads"
Is there any explanation why MacOs separates these two folders ? Why won't the system keep the full back-up in one folder ?
P.S. So to be able to restore completely my emain history I have to back-up BOTH folder V2 AND Mail Download ?
I am not sure why Apple placed these in separate folders; it could have placed them within the same folder. Mail is sandboxed, so technically it accesses all of these folders either directly in the Containers folder, or through aliases (i.e., for the Mail Downloads folder) from within the Containers folder. However, sandboxing is a separate detail here.
To ensure all of the Mail data is preserved as-is on your system, you will need to back up both folders; however, if you use a complete system backup like Apple's Time Machine service, or a cloning tool, then you will not have to bother with doing this manually. This is the route I recommend to establish a backup routine, as it will ensure you get everything.
Right. When Mail downloads messages from the server, it includes the attachment as well. These are in the standard mailbox structure. When you open the attachment then it is placed in the Mail Downloads folder and opened from there. If you have not saved the attachment elsewhere, but have opened it for viewing and during this time you delete the initial message, then the one on the Mail Downloads folder will be the only message you have opened. This allows for you to continue managing your email without interruption, regardless of the status of the attachments you're currently interacting with. In this manner, the Mail Downloads folder is simply a cache.
But dear mr. Topher Kessler could you plese explain why do I "...need to back up both folders..." if Mail Downloads folder is simply a cache folder? What information does it posses that is required by mail.app to restore the whole message history? And why isn't it to be regulary cleaned . . .
By the way, I have found folder "User->Library->Mail->V2->Mailboxes->*the name of my mailbox*->...->Data->...->Attachements & Messages". And this folder named "Attachements" contains all the attached files, shown in mail.app in the mailbox !
Therefore the role of "Mail Downloads" becomes even more complicated for me . . .
Well, thats another exciting question In my point of view IMAP protocol is not reliable, because in case the server's data gets corrupted, mail.app will sync with IMAP and all my mail structure will fail without possibility to recover. And there is nothing I can do with it
And what I like in POP - I am responsible myself for the safety of all important information. And in case my file system becomes corrupted, I can always easily restore it from online storage / external back-up drive.
But anyways, as I have already said....this is another topic )) I do not feel like I am fanatical about back-up, I just don't like the way time machine works, and all I need to learn : is Mail->V2 the only folder that I need to restore everything in case of some fail?
Okay lol I have finally found an answer in google :
- If you double click on an attachment icon in a Mail message, or do Quick View, it will download a copy of the attachment to your user directory > Library > Mail Downloads.
- If you Save the attachment you will have a second copy downloaded to the location specified in Preferences > General > Downloads folder:
- To automatically delete the extra copy in Mail Downloads, change Preferences > General > Remove unedited downloads: to 'when Mail Quits'. Any file placed in the folder "Mail Downloads", which you haven't modified will be deleted.
The Mail Downloads folder is now cleaning reuglary, just as it seemed logical to me in the begining of the thread )
Data in V2 folder is all I need to backup to be able to restore completely everything in my mail.app
Thank everybody for your time!