05-13-2019 08:18 PM
05-13-2019 08:18 PM
I have a Teams channel setup to accept emails from anyone (as in, there are no sending domain filters set).
If I email this channel directly from my Office 365 or GMail accounts, the messages are displayed. However when I route the email from a smart-host (it's a custom setup, not an off the shelf package) then the message doesn't get through.
I can setup the smart host to send to my Office 365 mailbox address and the Teams address at the same time - I get the message but Teams does not.
Does anyone know if Teams is checking DKIM signing on the message, or if there's a SPAM filter of some kind? My smart host does not (yet) apply DKIM signing to the messages it routes, so I'm wondering if that's the issue.
The SPF records are set properly but the message content I've been using has been "test" this and "sample" that, which can end up in Junk sometimes.
05-13-2019 10:14 PM - edited 05-13-2019 11:42 PM
05-16-2019 02:00 PM
05-16-2019 02:14 PM - edited 05-16-2019 02:18 PM
05-17-2019 03:47 AM
Thanks @Christopher Hoard - that's not quite what I meant.
Firstly, the "smarthost" is of my own making and isn't greylisting anything. It's a mail router that you can send email to and will forward that email on to another mailbox for you. I have setup a rule that the target for the router is a Teams email address (and an Outlook mailbox - I can have more than one target). The Outlook mailbox receives the message, so the router is obviously working, but the Teams channel never does. This means the Teams mail feature must be rejecting the message.
I noticed that the router does not strip out the original DKIM headers when the mail comes in. This means the message would definitely fail DKIM validation. That's enough to send the message to the Outlook spam folder... I wonder if it's enough to also prevent the message from getting through to Teams.
I have a new build of the router that I'm testing that resets the DKIM headers properly - we'll see if this solves it!
05-17-2019 03:50 AM
@Chris Webb So we updated the message router so it now properly signs messages with DKIM; I also have the system emailing me copies of any messages that come through. So I **know** the messages are being sent on to the Teams channel, but they never appear in the list.
Is there any way to debug this? Messages sent to Teams are not ever getting into the channel which is a serious problem for us right now.