Folders and syncing: why you have two "Sent" folders

Module 3: Managing your mailbox · Reading time: 9 minutes

Learning objective: After this lesson you can explain how IMAP folders work on the server, make your mail program use the right special folders, and prevent mail from appearing twice or going missing.

Key concepts: IMAP folder, folder list on the server, special folders (Sent, Trash, Drafts, Spam, Archive), special-use (RFC 6154), folder mapping, subscribing to folders, deleting and permanently deleting (expunge), sync period, offline copy

Where are your folders, really?

In lesson 1.3 you saw the difference between IMAP and POP3. With IMAP your mail is stored on the server, and your mail program shows what is there. The same goes for folders. If you create a folder called "Quotes" in Thunderbird, Thunderbird creates that folder on the server. Your phone will then see it too, and so will webmail.

That is exactly what you want. But it also means a mail program can create folders on the server that you never intended. And if two programs disagree about what a folder is called, you end up with two.

A few things to know about folders on an IMAP server:

• The Inbox is always called INBOX on the server. It is the only folder with a fixed name. Your program displays it as "Inbox", "Inbound" or a name in your own language.
• All other folders can have any name. The server has no "real" Sent folder unless it says so itself (see below).
• Subfolders are separated by a character, usually a full stop or a forward slash: INBOX.Offertes or Offertes/2026. You rarely see this, but it explains why some programs put all folders under the Inbox.
• A program sometimes only shows the folders it is subscribed to. A folder that does exist on the server, but that you are not subscribed to, then seems to have disappeared.

The problem with special folders

Your mail program needs a few folders to do its job:

Every program has its own preference. Apple Mail uses different names by default than Outlook, and Outlook different ones again than the Gmail app. Set up your mailbox on three devices without paying attention, and this can happen:

• Outlook puts sent mail in Sent Items.
• Your iPhone puts sent mail in Sent Messages.
• Webmail puts sent mail in Sent.

Now you have three Sent folders, and on each device you only see part of what you have sent. This is the most common complaint about IMAP: "I can't see on my phone what I sent from my computer".

The solution: special-use

Since 2011 there has been an IMAP extension that lets the server indicate which folder is for what: special-use (RFC 6154). The server then says, for example, "this folder is called Sent and has the role \Sent". A modern mail program adopts that and no longer creates its own folder.

Most mail servers support this, and so do most programs. But it still often goes wrong with:

• a mailbox that has existed for years, in which old programs have already created their own folders;
• a mailbox that was moved from another provider, where the folders had different names;
• programs you set up manually before the server offered special-use;
• POP3 (there are no folders on the server, so each device keeps its own Sent folder locally).

Mapping the folders yourself

Do you already have duplicate folders, or are you not sure? Then choose one folder per role and tell each program which folder that is. Preferably choose the folder the server itself designates. You can recognise it in webmail: the Sent folder is usually near the top there, with its own icon.

Where do you set it?

• Thunderbird: Account Settings, your account, Copies & Folders (Sent, Drafts, Archives) and Server Settings (what happens to deleted messages, and which folder they go to).
• Apple Mail on the Mac: Settings, Accounts, your account, Mailbox Behaviors. On the iPhone: Settings, Mail, Accounts, your account, the account itself, Advanced, and then choose the folder on the server for each role.
• Classic Outlook: for an IMAP account, go to the account settings (More Settings, Advanced) to choose the root folder path and the folder for deleted items. For sent items, classic Outlook offers no choice in many versions: it uses the folder the server designates, and otherwise its own.
• Gmail app: uses the folder the server designates; you cannot set it per folder.

Then move the mail from the unnecessary folders to the chosen folder, and delete the empty folders. Do this on one device (preferably webmail or your computer) and wait for the other devices to pick up the change.

Deleting works in two steps

With IMAP, deleting is really setting a flag. A message gets the deleted marker (\Deleted), but is still on the server. Only when the program issues the expunge command is it really gone. Most programs work like this:

1. You press Delete. The program moves the message to the Trash (in fact: it copies it to the Trash and marks the original as deleted).
2. The original is permanently removed (expunged) straight away or when you close the program.
3. Only when you empty the Trash is the message gone from the server.

Some programs are set up differently. You then see messages with a line through them that never go away: they are marked, but never permanently deleted. And they still count towards your storage. In that case, look in your program for Compact Folder (Thunderbird), an option to remove deleted messages, or a setting such as "permanently delete deleted items when leaving the folder".

Important: deleting on one device means deleting on all devices. That is the whole point of IMAP. If you want a message off your phone but kept on your computer, IMAP cannot do that. At most you can sync a shorter period on your phone (see below).

Has something gone missing anyway? Many providers keep backups from which a mailbox or folder can be restored, but usually only for a limited period. Don't rely on that as an archive.

How much do you sync?

A mail program does not have to download everything. On a phone it is often handy to sync only the last few weeks, or to have only the Inbox pushed. That saves space and battery. It changes nothing on the server: the old mail is still there, you just don't see it on that device.

On a computer, most programs make an offline copy of the mailbox (Outlook in an .ost file, Thunderbird and Apple Mail in their own folder). That is a copy, not a backup: if you delete something on the server, it also disappears from the offline copy. A real local storage place is a folder you create yourself under Local Folders (Thunderbird), On My Mac (Apple Mail) or in a .pst data file (Outlook). Whatever you drag there is no longer on the server. More about this in lesson 3.2.

In practice: how it looks in a panel

In WebOké's webmail (Roundcube) you see all the server's folders on the left. Under Settings, Folders you can create, rename and delete folders, and switch a subscription on or off. Under Settings, Preferences, Special Folders you can see which folder is used as Sent, Drafts, Trash and Spam. At WebOké the server designates the Junk folder as the spam folder, and webmail shows it as Spam. You can read more in the article about folders in your mailbox. Other providers work in a similar way; their webmail may have a different name, but almost every webmail has this kind of folder management.

Summary

• With IMAP your folders are on the server too. Every device sees the same folders.
• Only INBOX has a fixed name. Sent, Trash, Drafts and Spam have different names in each program, unless the server designates them (special-use, RFC 6154).
• You fix duplicate Sent folders by choosing one folder per role and pointing every program at it.
• Deleting with IMAP means marking and then permanently removing (expunge). Marked messages still count towards your storage.
• An offline copy is not a backup; a local folder is a separate storage place.

Quiz

Exercise

Exercise O3.1: Checking your folders. Open your mailbox in webmail and on every device you use it on. For each device, note which folder it uses for Sent, Trash, Drafts and Spam. Do you have duplicate folders? Choose one per role, point every device at it, move the mail and delete the empty folders. Then fill in the checklist and answer the question: which folder did the server itself designate, and how did you recognise that?

Further reading

The steps in these articles apply to WebOké's panels; other providers work in a similar way.

• DirectAdmin guide 8.7: IMAP or POP3: what's the difference?
• IMAP or POP3: what's the difference and which one should you choose?
• DirectAdmin guide 18.11: An e-mail was accidentally deleted
• Restore mailbox or deleted emails from the backup
• RFC 6154 (IMAP LIST Extension for Special-Use Mailboxes)