​Error: [ALREADYEXISTS]

This error indicates that your IMAP server is not RFC-compliant and is getting confused about folder names because of "silent" renaming. It can also mean that a user disabled IMAP access to a folder at the Destination. This error message can come with different error messages ("mailbox" in IMAP terminology actually means "folder"):

• "Duplicate folder name"
• "Folder name conflicts with existing folder name"
• "Mailbox exists"

Here are a few examples illustrating the problem:

Example 1:

1. The Source has two folders, F1 and F2, with similar names (for example, foo-bar and foobar).
2. We create folder F1 at the Destination (foo-bar).
3. The Destination creates F1 slightly differently (for example, special characters are replaced, so foo-bar gets created as foobar).
4. We create folder F2 at the Destination (foobar).
5. This conflicts with F1, which was created as foobar (even though it was foo-bar), and the Destination says the "mailbox already exists".

Example 2:

1. The Source has a folder F1 (foo-bar).
2. We create a folder F1 at the Destination (foo-bar).
3. The Destination creates F1 slightly differently (for example, special characters are replaced, so foo-bar gets created as foobar).
4. Later, you perform a Delta Migration pass.
5. We find that folder F1 is not present at the Destination (there is no foo-bar, only foobar).
6. We try to create folder F1 again, and the Destination says the "mailbox already exists".

Example 3:

1. The Source has a folder F1 (for example, blah).
2. We create a folder F1 at the Destination (for example, blah).
3. The user disables IMAP access at the Destination.
4. Later, you perform a Delta Migration pass.
5. We find that folder F1 is not present at the Destination (there is no blah).
6. We try to create folder F1 again, and the Destination says the "mailbox already exists".