One of my long term customers called me with a complaint about his daughter. No, I don't do family counseling; this was about a company wide email message that was being duplicated over and over again. When he called me, he already had several hundred copies of the email she had sent and so did every other person in the company.
Duplicate email usually has a simple cause: the sending end never got an acknowledgement from the server that the message was received intact, so, assuming the worse, it sends it again. If, however, the receiving server thinks that it got everything and that it did send an acknowledgement, it will get busy passing that message on to the recipients. When the next message comes, it happily passes that on too.
You wouldn't expect this to keep happening. Sure, something might go awry once or twice every now and then, but not hundreds of times.
We do often put some limits on this dance. For example, we'd usually set a hard limit on the number of messages per hour from one IP address. This will at least slow down errors like this.
The cause of this could be faulty software or a bad network connection. I'd look to the sending machine's network card or cable as the cause, but even that would be very strange: it's hard to be defective so that the acknowledgement is missed without being so defective that nothing works at all.
If this were happening to multiple people, I'd look to an SMTP protocol inspector at the firewall messing this up. In my experience, that particular interference would be with large attachments, not small text message as this one was. Also, that usually wouldn't repeat more than a few times.
In this case, her father knew that she was out of the office and therefore had to be using her cell phone. I therefore suggested the quick solution: nuke the email account on her phone.
That's not as draconian as it sounds. All data is stored on the server; the phone account can be set up again in less than a minute. Killing the account will quickly stop any sending and if it didn't, killing the account and shutting the phone off surely would. So that's what we did and of course the duplicate emails stopped.
It's not hard to find accounts of others having similar problems. Those referenced Exchange servers, but ActiveSync is the common factor. It could be the phone software, but it could also be the network connection - perhaps she was in a bad reception area when she sent the message - though, again, it's hard to imagine why the message would get sent and only the final part of the communication get screwed up.
Anyway, problem fixed with nothing more than a quick phone call. I thought we had put that behind us, although she would have to test her phone and be sure it was not faulty software.
Two weeks later, Dad called again. This time he told me that his daughter couldn't access her email. I asked if he meant from her phone; no, she had not even restored her account yet. She was unable to see mail on her desktop not twenty feet from the server room.
We felt that warranted a hands-on visit. I could have VPN'd in, but they are not that far away and I had some shopping to do along the route anyway, so I headed on over.
When I arrived, I was momentarily puzzled. Looking at her mail directory in the Kerio Connect store directory, I could see that it contained well over 200,000 files. However, her Inbox, Sent Items and Deleted Items were all small - less than 200 messages in any of them. The largest email folder in her directory had 7,500 messages and the total of everything was less than 10,000. So where were all these files?
I found them in Calendar - over 200,000 entries.
Of course calendaring is a separate part of Active Sync - nuking the email account wouldn't affect that, and apparently this phone was having the same trouble with Calendar events as it had with email - it had been sending them repeatedly for two weeks and that finally broke her mail client.
I deleted these from the command line, and then told the system to reindex her mailboxes. The deletion and the reindexing took about 30 minutes but she was able to get in after that.
Although Kerio recommends shutting down the server in these cases, I didn't. I had her close her email client and shut off her phone; there was no danger of calendar events arriving from anywhere else so I saw no need to inconvenience the rest of the company. Still, recommended practice is to bring the server down.
I told her she could try reactivating her account if it was OK with her father and told him that if he did that, he should watch her mailbox closely for a few days just in case. We need to find out if her phone is broken or this was just a transient glitch. My suspicion is the phone because of the calendar entries building up over time. It doesn't seem to be transient, and the similar circumstances I can find in Google indicate that something is broken in the phone software. If she reactivates her email and that starts acting up immediately, that would seem to nail it, although I'm not sure what she'd do at that point: I didn't find any definite solution in my Google searches.
Strange problems like this on Android are often the fault of the email client. 'MailWise' or 'Touchdown' are better clients and worth trying if you have odd Android mail issues.
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