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tells VM to retrieve all the messages in the IMAP mailbox regardless
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of how many messages there are and how large the mailbox is.
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@cindex expunging, IMAP messages
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@findex vm-expunge-imap-messages
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After VM retrieves messages from the mailbox, the default action is to
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leave the original messages on the server unchanged. They can be
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@unnumberedsubsubsec Multiple access to IMAP spool files
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A principal idea behind the IMAP protocol is that messages can be
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retained on the server so that you can read them from multiple
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locations, e.g., from office and home, or from other places on the
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Internet while you travel. If you access your IMAP mailbox from
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multiple locations then you would need to plan your strategy for
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expunging messages carefully. For instance, if you access your work
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mailbox from home, and both your office machine and home machine
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expunge messages after retrieving them, then some of your mail will
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end up on your office machine and some on your home machine. That is
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unlikely to be a successful strategy.
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The best way to access IMAP mailboxes from multiple locations is to
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use the facility of IMAP folders. (@xref{POP and IMAP Folders}.)
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However, if you prefer to download all mail to local folders, then
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your best bet is to designate one of your machines as the principal
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location for downloading mail and treat the other machines as
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temporary mail reading sites. In that case, you should set the
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principal downloading location to expunge messages on the server and
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set the other reading sites to leave the messages on the server
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intact. You can also manually run @code{vm-expunge-imap-messages} if
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you are careful to remember which site should expunge messages and
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which site should retain them.
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@cindex X-VM-IMAP-Retrieved header
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VM remembers the messages you have downloaded from an IMAP spool file
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so that it can avoid downloading them again on your next visit. The
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list of these messages is written into a special mail header titled
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@code{X-VM-IMAP-Retrieved} in your mail folder. When you expunge IMAP
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messages, their entries are deleted from the list. However, when you
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designate one of your machines as a reading site and never expunge
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messages from there, then the @code{X-VM-IMAP-Retrieved} header on
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that machine will only grow over time. When the list gets excessively
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long, it will slow down the saving of folders.
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@findex vm-prune-imap-retrieved-list
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To avoid the problem, you should prediodically run the command
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@code{vm-prune-imap-retrieved-list}. It will examine the IMAP server
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to see which messages still exist and retain only their information in
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the @code{X-VM-IMAP-Retrieved} header.
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@node Index Files, Folder types,IMAP Spool Files, Local Folders
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700
@unnumberedsubsec Index Files
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701
@cindex index file