How does BIS work?

Hi, we have a new BB Curve from Verizon, and are having intermitant trouble receiving emails on it. It works sometimes, so I am assuming things are setup correctly.

Can anyone explain how the BIS works for email with POP accounts? Does the service poll the POP server of your provider ever so often and look for new mail, or how does it work?

I figure, that with a little better understanding of how BIS handles this could help me figure out why sometimes emails don't make it at all, or are delayed.

Thanks,
Bozz

You seem to have grasped the basic concept behind BIS.

There are several places it can go wrong;
The BIS server may be unable to reach the mail server.
The mail server might refuse the BIS server because you (human) are reading the mailbox so it is locked.
The BIS server may have a problem passing traffic to the cellular systems which are serving your particular phone.
Your phone might be off network or unable to handle data traffic due to overload or bad radio conditions when the system tries to deliver mail. On most cellular networks "data" is a second class citizen and voice traffic gets priority.
You might be on the phone when the message delivery attempot is made. (At least on GSM/2G systems this blocks data. Not sure about your CDMA, and on 3G it can background receive during a voice call).

All of these are "expected failures" and the system is designed to handle fail gracefully and try again later.

Mailbox password failure is the only condition I know where human intervention is required to restore normal operation.

Some ISPs were in the habit of blocking BIS servers because regular checking uses more bandwidth than a human reader. This mostly impacted IMAP operators, and AFAIK it is not a frequent problem. IIRC the usual fix from the user side was to reset the (same) mailbox password at the BIS server, which would trigger it to resume checking until it got kicked out again.

Originally Posted by branta

You seem to have grasped the basic concept behind BIS.

There are several places it can go wrong;
The BIS server may be unable to reach the mail server.
The mail server might refuse the BIS server because you (human) are reading the mailbox so it is locked.
The BIS server may have a problem passing traffic to the cellular systems which are serving your particular phone.
Your phone might be off network or unable to handle data traffic due to overload or bad radio conditions when the system tries to deliver mail. On most cellular networks "data" is a second class citizen and voice traffic gets priority.
You might be on the phone when the message delivery attempot is made. (At least on GSM/2G systems this blocks data. Not sure about your CDMA, and on 3G it can background receive during a voice call).

All of these are "expected failures" and the system is designed to handle fail gracefully and try again later.

Mailbox password failure is the only condition I know where human intervention is required to restore normal operation.

Some ISPs were in the habit of blocking BIS servers because regular checking uses more bandwidth than a human reader. This mostly impacted IMAP operators, and AFAIK it is not a frequent problem. IIRC the usual fix from the user side was to reset the (same) mailbox password at the BIS server, which would trigger it to resume checking until it got kicked out again.

Thanks, I appreciate your response.

Do we know how often BIS checks the POP accounts for new messages? And, is this a user adjustable setting?

Thanks,
Bozz5384

Posted from my CrackBerry at wapforums.crackberry.com

There's a rumor for 15-20 minutes on a POP3 connection where the BIS server has to initiate a new connection every time and *must* disconnect after checking. IMAP is similar in theory, but many IMAP servers now implement IDLE, so if the session hasn't been timed out email pickup can be almost immediate.

My tests showed it to be 20 minutes.

I use mine for business. My business uses POP email, so BIS is necessary. I have my work email copied to my BlackBerry email address. That way it is sent to my BB immediately. I then set my work email as my reply to email address for my BB email address so when I reply it comes from my work email.

A little convoluted, but necessary to get instant delivery of my POP based work email.

Another common cause of intermittent email delivery to a BB is some other mail client (most likely a desktop) retrieving and deleting the email before the BIS system polls for it. The BIS polling interval is 15 minutes (according to my mailbox access logs). If your "other client" retrieves and deletes email immediately prior to BIS polling, BIS will rarely see any new email. If the order is reversed, BIS will rarely miss any new email. Most situations are somewhere in between.

To correct this issue you have to configure your "other client" to leave messages on the server for some period of time. Usually a period of 1-3 days will work fine.

I don't know if any of this applies to you, but this is ONE possible explanation.

The 15-20 minute polling is interesting, because I find a lot of emails arrive on my BB before the destination such as if I'm sending something from home to work or vice-versa.

RIM is pretty good about letting you know if there is a real email issue. My work email is MS exchange server requiring a pretty hefty password which must be changed every three months. Invariably something gets messed up and I get a message from RIM that my email is not working. The same is true if your email system is down, which has happened both at work and home.

it takes about 15 min for my pop3 emails to arrive i wish that i could get them sooner but guess i will have to live with it.:confused:

Thanks, you guys have answered my questions! Now that I know it is 15-20 minutes between when it polls for it, I can change some things around and make it work.

I believe now that the desktop was pulling down the messages before the BIS was getting them.

Thanks,
Bozz5384