The mailbox format used by Mail changed drastically in Mac OS X 10.4 (Tiger). Mail 2.x knows about the old format and can import or convert in place mailboxes created by Mail 1.x, but Mail 1.x obviously knows nothing about the new format used by Mail 2.x. Actually, the conversion from Mail 1.x to Mail 2.x mailboxes is broken and Mail 2.x sometimes can only import Mail 1.x mailboxes as
Other, but that’s another story...
Mail stores the mailboxes in
~/Library/Mail/. Although
.mbox packages appear to be files in Mac OS X 10.3, they’re actually folders just like in Mac OS X 10.4. Ctrl-click on an
.mbox package and choose
Show Package Contents from the contextual menu to see the files it contains.
For each mailbox, Mail 1.x stores all the messages in a single file in standard mbox format (the
mbox file within the
.mbox folder/package), whereas Mail 2.x stores messages in individual
.emlx files within a
Messages folder that Mail 1.x knows nothing about.
The only way to transfer Mail 2.x mailboxes to Mail 1.x is by first exporting or converting them to a (standard mbox) format that Mail 1.x understands. Standard mbox files can be imported into most mail clients. In particular, they can be imported back into Mail (any version) doing
File > Import Mailboxes and choosing
Other / Standard mbox as the data format.
If you have access to those messages on a computer running Mac OS X 10.4 (Tiger), you may export them in standard mbox format by selecting the messages in Mail, doing
File > Save As and choosing
Raw Message Source from the
Format popup menu. Andreas Amann’s
Mail Scripts has an
Archive Messages script that you might also find useful to export all the mailboxes.
On a computer running Mac OS X 10.3 (Panther), you need something like
emlx to mbox Converter or
Emailchemy to convert the
.emlx files to standard mbox format.
Note: For those not familiarized with the ~/ notation, it refers to the user’s home folder. That is, ~/Library is the Library folder within the user’s home folder, i.e. /Users/username/Library.
