Randomized Ghost Notifications


NethServer Version: 7.2009
Module: nethserver-mail

I have a instance with about 60 users, some users (not all) are reporting that they are receiving “ghost notifications” for emails.

We’ve not established a full pattern yet, but basically what’s happening is that a user will get a notification of a new email on their phone… Click the notification and the mail client will respond that the email doesn’t exist or couldn’t be loaded.

However, if the user logs into SOGo Webmail, the email is sitting in the inbox as it should be. Is anyone else having this same issue or has dealt with it?

I’m at a loss for what to even check because the logs show nothing wrong. And they show the emails being delivered to the inbox.

In 9 out of 10 situations the sending user is an internal user that is on the same email domain as the recipient.

Everyone is using the same email client on the phone?
Which kind/brand of smartphone is?

So this isn’t specific to a phone model, carrier, or client. And it’s not every single user that is reporting the issue.

It seems to happen with Both IOS and Android, users have reported issues with Outlook for Mobile, Apple Mail, and BlueMail.

Although IOS seems to be more common as far as platform.

Antispam is configured on server?
Are any mail rules configured via SOGo?
Email clients are configured as push?

Anti-Spam is handled by an external server.

Wouldn’t SOGo rules apply on a per users basis? Not all users reporting issues utilize SOGo.

The mobile email clients are configured as push.

My current guess is that push notifications might be ghosts triggered when server starts to pull emails from antispam service.

With antispam on nethserver configured, could be this sequence:

  • message received
  • push notification sent
  • antispam evaluate message as spam → move it to spam or trash folder
  • now notification is targeted to a “missing” message from inbox.

I know that’s not the “real” answer to your issue… Could a person switch setting from “push” to “every 5 minutes”?

So it’s funny you say that because I was thinking the same thing. But we don’t have the anti-spam enabled in Nethserver, just anti-virus.

The external filter is Barracuda, if it makes it to Nethserver there shouldn’t be any server based filtering until it hits the user level (folders, etc).

I made a few changes to the nethserver-mail package, namely reinstalling it, and then enabling and disabling everything again (just in case there is a stuck setting somewhere).

Is there anything formatting wise that would cause issues? What I find the most strange out of all of this, is that a user will get a notification on their phone…click it and then get a message that the email doesn’t exist or couldn’t be loaded… But if they load up SOGo, or another webmail client… The email is there…

On so various panorama of OSes and email applications?
I feel unlikely about “formatting”. On the other hand…

Would you kindly tell me how Barracuda interacts with NethServer? I never used that kind of product.

Would you please anyway try the “5 minutes” setting on at least one smartphone? Reboot the device after changing setting on email client.

Last but not least: are you using hotsync or IMAP?

The long and skinny is that Barracuda filters out spam. Once the email passes the filter (which most do), the email then gets passed off to Nethserver and processed as normal.

In terms of outgoing email, anything thats inter-domain (domain.com to domain.com addresses) don’t hit Barracuda, they just go straight to where they’re supposed to be delivered.

Anything that is external (domain.com to gmail.com) will pass through Barracuda as an outbound relay.

The 5 minutes sync, I believe is already set up on most devices (that’s how we have it documented in a setup instructions to our end users).

I am not using HotSync, and any user that is not connected via SOGo, is connected via IMAP or ActiveSync. Most mobile users are using IMAP.

Ok… thanks for the explaination.
However this do not make me know how NS7 can “use” Barracuda. It’s a firewall that filters automatically every mail-related connection? Is a mailserver? A proxy?

Sorry, so Barracuda is an off-site cloud based solution. It’s not really a proxy, it’s a relay. All incoming emails hit Barracuda first, once they pass the spam filtration they’re released out to Nethserver which then takes the email and delivers it to the local user directly. If the email address doesn’t exist in Nethserver, it bounces back to Barracuda which shows why it bounced back.

Hopefully that clears up that.

Also, just realized I should probably mention this:

The emails that are affected here are internal emails. So they do not touch Barracuda.

For example, assuming domain.com is my email domain, an email from joe@domain.com to tom@domain.com won’t touch Barracuda. It’ll just get delivered to Tom… These are the ones that we’re seeing problems with.

An email from joe@domain.com to alice@company.com will go through Barracuda’s outbound relay. And an email from alice@company.com to joe@domain.com will pass through Barracuda (as long as it’s not flagged as spam) and then just get delivered to the inbox.