POP3 Connector Schedule

Discussion in 'Windows Small Business Server' started by Jay, Jul 8, 2006.

  1. Jay

    Jay Guest

    is there any way to lower the pop3 connector schedule from the default 15 to
    say 5 minutes?

    Jay, Jul 8, 2006
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  2. Many have asked this question, without realizing its implications:

    If the number of minutes is set too low (say, 5 minutes or less), an email
    with a large attachment (say, 9mb) might not get completely received within
    the timeframe, causing a error and another attempt to retrieve the same
    message, repeating.
    Greg Kirkpatrick, Jul 9, 2006
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  3. Jay

    David Powell Guest

    There is a way to do this, you have to add an accelerator dword to the

    Add a ScheduleAccelerator (DWORD) entry to


    To determine the actual polling interval: Divide the POP3 Scheduling
    interval (the value you have configured in the POP3-Connector
    GUI'sScheduling tab) by the value you set for the ScheduleAccelerator reg
    entry. For example, if you specify a 15-minute interval in the
    POP3-Connector GUI, and you set the ScheduleAccelerator value to 3, the POP3
    Connector will poll every 5 minutes (15 divided by 3). If you set it to 5,
    the POP3 Connector
    will poll every 3 minutes.

    This is unsupported by Microsoft and it is said that it should only be used
    in a testing environment.

    I used it and removed it after a couple of days as it was causing numerous
    errors with exchange. Some people use it and say it has worked for years
    with no problems.

    Try it and see how you get on but heed everyones warnings.

    David Powell, Jul 9, 2006
  4. I have heard this explanation before and it makes no sense to me. The
    reasoning seems to be that tasks to download mail are kicked off at the
    regular interval, and if the interval is too short then, as you say, a
    message might not be completely downloaded and deleted from the server
    before the next task is started. But this makes no sense. Surely it cannot
    be beyond the whit of man to check to see whether the previous task has
    completed before starting a new one? This is how every desktop POP3 client
    mail program works (click "Send and Receive" repeatedly in Outlook Express;
    you do not get multiple simultaneous download threads, and you don't receive
    duplicate messages).
    Matthew Kendall, Jul 9, 2006
  5. Jay

    Joe Guest

    Certainly if you trigger collection manually before the previous
    connection is broken, it doesn't happen and you are told why. It
    does seem difficult to believe this doesn't happen to scheduled
    Joe, Jul 9, 2006
  6. you wanna bet???

    I run mailboxes on a slow connection, my family POP mail from my LoungeAN
    SBS (actually, I've managed to swing one sister to RPC over HTTP, the other
    prefers POP). The most frequent mail related issue I get from them is that
    they have a large email (one of their kids has taken some photos) in their
    mailbox and it is not transferring inside the scheduled check time. I tell
    them 'OK, click the icon in the bottom right corner of Outlook, how many
    tasks are there?' there will often be a dozen or more queued tasks.

    This is also a major issue for a client. They don't have SBS and all
    workstations POP from their hosted service via their 1500/256 ADSL.
    Regularly they call, 'our internet's playing up', almost invariably it is
    because a large item has been emailed to a user who has, against my
    recommendation of not checking the POP box more often than 15-20 minute
    intervals, set Outlook to pull every 5 minutes (then when someone calls
    'Have you got it yet?' they hit send/recv repeatedly, not knowing that the
    transfer is already in progress). In this case it often results in the POP
    box going into what is known as a 'POP Lock' condition, once the mailbox is
    in such a lock any attempt to access the mailbox causes the condition to
    last longer, the ISP _cannot_ manually clear the condition (well, they
    probably could by bumping several thousand users off the affected server,
    not likely). It's even better when the sender has emailed to all, 11 copies
    of 7MB fighting to come across the connection before Outlook signals a POP

    There are very good reasons why you should not check a POP box more
    frequently and though you might think 'mail is important, I need it
    immediately' you are fooling yourself. Even in the case of delivery via SMTP
    delays occur, email was never designed to be an immediate delivery service.
    (nor was it designed to handle multimegabyte content, but that's a story
    better left to another thread)
    SuperGumby [SBS MVP], Jul 9, 2006
  7. POP will not deliver bcc emails... everyone does realise that right?

    You are running a business and you will lose emails by using the pop
    connector. As long as everyone realized that pop passes the password in
    cleartext and that you wlll lose emails....
    Susan Bradley, Jul 9, 2006
  8. Jay

    Joe Guest

    It depends on both your ISP and POP client. The problem with POP3 is
    that when SMTP mail reaches the POP server, its envelope is thrown away.
    POP doesn't use it, because the SMTP server has already placed the mail
    in the recipient's mailbox.

    Multidrop POP3 keeps all the mail for one organisation in a single POP
    mailbox, or at least conceptually. A multidrop POP3 downloader must use
    the email headers to distribute mail correctly within the organisation
    (or readdress them and pass them on to the organisation's SMTP server,
    which is more usual).

    By definition mail sent with a bcc recipient does not contain that
    recipient's name in the headers, or the other recipients could see it
    and it wouldn't be blind. Mail to the main and cc recipients, if they
    are in one organisation, is only sent once, and the receiving server
    distributes it. If the message has bcc recipients, there are additional
    copies sent, with the SMTP envelopes addressed to the bcc recipients.
    There is no problem with the bcc recipient being able to see the other
    recipients, or else they would all have been sent bcc. Since the POP
    server has discarded the envelope there is no address for the POP
    downloader to send it to.

    An ISP can arrange for his SMTP server to place the envelope address in
    a new email header (any transport program can add headers, but not
    remove them) and a suitable POP client can use this header to correctly
    address bcc mail. Typically it will be called X-Envelope-To, the X
    signifying a custom header which is not part of the email standard.

    My own ISP handles multidrop POP3 very well, adding a suitable header
    and indeed extending the POP3 protocol a little. The POP3 downloader
    I use, which does not run on Windows, has a special mode of operation
    when used with this ISP, so my POP3 email works. In fact, it works a
    little too well, as most of my email does not contain any of my user
    names in the headers, but still gets delivered. Yes, the spam. Still,
    because nearly all is not to a valid user, it's easy to deal with.

    Mailing lists normally use the bcc technique, as it is not desirable for
    subscribers to know who other subscribers are. Mailing list programs
    therefore send email as multiple SMTP messages with no proper recipient
    (or to the list itself) and so standard POP3 also has trouble here.
    Joe, Jul 10, 2006
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