Is there a limit to the amount of folders you can create in Outlook?
I need to support a lot of folders for something I want to do, but I don't want to hit a limit...
The actual answer is it depends.
If your mail is stored on Exchange, which is often the case in a corporate environment, you will be limited by how much space you have on your mailbox, and any restrictions put on the server by it's administrators. In this scenario it would be best to contact them and ask them if they have any limitations.
If it's local to your machine, in a PST file, then the only limitation is the amount of disk space you have to store data. The number of folders are not restricted.
Be careful however, a lot of folders can become hard to manage, and can become an issue when using a mobile device or web browser to access your account if it is on a corporate network.
Early versions of the Exchange client supported about 16,000 items per folder. Outlook, with large table support enabled, supports about 65,000 items per folder. (Large table support is the default for new pst’s created since Outlook98.) Outlook 2003 with a Unicode format *.pst or *.ost can have an unlimited number of items.
These limits apply to all folder types and subfolders count as ‘items’, so you could have 60000 folders and 5,000 messages, with each of the 60,000 folders containing 65,000 messages, at least until you hit the ANSI pst size limit of 2GB.
Exchange mailboxes should not be affected by these limits, except when using it offline.
As your folders (and the mailbox) grows, it tends to slow Outlook down, so while you can have 65,000 contacts, you may not want quite that many.
The real answer is: There is no limit for "how many folders" you can have. The limit of the mailbox may be unlimited, depends the Exchange admins... And the 20Go PST files. 2Go if it's an 97-2002 format.
The problem comes in "searching" Outlook is currently hard code limited to 64 subfolders for indexing/searching after that weird stuff starts happening.