Do you have a Pop or IMAP mail account?

Pop mail accounts can only connect to server and see the Inbox. Emails are downloaded from server Inbox to mail account Inbox.

re: 'For example If I create a folder and move some of my mails there,'

Did you create the folder in Thunderbird or in webmail?

Do you have this setting? View > Folders > All

it is Imap. Does that mean I can never see other folders?

Yes folders are set to view all

IMAP mail accounts can see any folder on the server. You can control which folders are visible. You "subscribe" a folder to make it visible, unless it's subscribed by default, or you disable "Show only subscribed folders". With Thunderbird you right click on a remote folder and select "subscribe" to get to the dialog box that lets you specify which folders should be subscribed.

More info on IMAP here:

• http://kb.mozillazine.org/IMAP
• https://support.mozilla.org/en-US/kb/imap-synchronization

How do I disable that setting? If I disable that setting will ALL of my folders show up?

If you uncheck:

• 'Tools' > 'Account Settings' > 'Server Settings' > 'Advanced' > "show only subscribed folders"

It will display all folders or you can select individual folders by right clicking on folder and selecting 'subscribe'.

The info 'Tools' > 'Account Settings' assumes you have enabled all your toolbars. Otherwise you can also access 'Account settings' via:

• '3bar menu icon' > 'Options' > 'Account Settings'

or

• right click on mail account in left Folder Pane and select 'Settings'.

THANKS A LOT. It worked like a charm :)