[Alpine-info] Running two copies of alpine - was Re: Gmail Access

Eduardo Chappa via Alpine-info alpine-info at u.washington.edu
Sat May 25 07:51:53 PDT 2024


Carlos and Chime,

the loss of a session due to locking has nothing to do with imap access
or not, it has to do with the way that the messages are stored.

First, let us talk about local access. In its default configuration
Alpine uses the unix format for local folders (except in Windows, where it
is called mbx, more about this later). The unix format locks the full
folder to avoid that two users modify the folder in incompatible ways.
This is the problem that Chime is experiencing. Since only one of the
alpine sessions can have a lock, one has to lose the lock and the other
one get it.

The unix format is also the default format for the UW IMAP server, so
when people access a folder in the unix format (typically inbox) through
the UW IMAP server, you will see the same issue that Chime is reporting.
In other words, the problem exists in this case because Chime is accessing
a folder that does not support concurrent access.

By the way, the reason why the second sessions steals the lock from the
first and the first does not retain its lock is exactly because of needing
to please IMAP users. Originally it was not possible to steal the lock.
Once a folder got the lock, no on could steal it, but this was contrary to
remote access, where users left their email open in the office, and they
could not access it later from home. So the University of Washington had
to make the last person to access the folder the winner of the lock.

The mbx format used by Windows Alpine does not have this issue. Every
session gets its lock and can be shared. You can have two alpine sessions
access the same folder at the same time and share all the information on
messages (for example, if a message is flagged "Answered" in one session,
it will also be flagged "Answered" in the other session without needing
to reopen the folder). If the UW IMAP server had the mbx format as
default, then concurrent IMAP access could be possible and the experience
that Carlos has with IMAP servers (such as Outlook, Gmail, GMX, etc.)
could be repeated.

In summary, the appearance that IMAP allows concurrent access but Alpine
does not is just that. Concurrent access has to do with if the storage
method allows concurrent access or not. So what we know is that Chime has
a folder that does not allow it (most likely a folder in the unix format)
while Carlos has share access (for a folder that is clearly not in the
unix format).

I hope this is enough information so that Chime can solve his issue.

--
Eduardo


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