Given that the information is in my mailbox and there shouldn't be any privacy concern around accessing it I looked at a few ways of getting access to these TeamsChat messages in OWA and Outlook the first way was using a SearchFolder. This did kind of work but because of a few quirks that the Hidden folder caused was only usable when using Outlook in online mode (which isn't very usable). The next thing I did was look a using an Addin which worked surprising well and was relatively easy to implement. Here is what it looks likes in action all you need to do is find an Email from the user you want to view the Teams chat messages from and then a query will be executed to find the last 100 Chat messages
https://outlook.office.com/api/v2.0/me/MailFolders/AllItems/messages?$OrderyBy=ReceivedDateTime Desc&$Top=30&$Select=ReceivedDateTime,bodyPreview,webLink&$filter=SingleValueExtendedProperties/Any(ep: ep/PropertyId eq 'String 0x001a' and ep/Value eq 'IPM.SkypeTeams.Message') and SingleValueExtendedProperties/Any(ep: ep/PropertyId eq 'String 0x5D01' and ep/Value eq 'firstname.lastname@example.org')
To break this down a bit first this gets the first 30 messages from the AllItems Search Folder sorted by the ReceivedDateTime
Next this selects the properties we are going to use the table to display, I used body preview because for IM's that generally don't have subjects so getting the body preview text is generally good enough to shown the whole message. But if the message is longer the link is provided which will open up in a new OWA windows using the weblink property which contains a full path to open the Item. One useful things about opening the message this way is you can then click replay and continue a message from IM in email with the body context from the IM (I know this will really erk some Teams people but i think it pretty cool and has proven useful for me).
Next this is the filter that is applied so it only returns the Teams chat messages (or those messages that have an ItemClass of IPM.SkypeTeams.Message and are from the sender associated with the Message you activate the Addin on. I used the Extended property definition for both of these because firstly there is no equivalent property and for the From address if you used orderby and the a from filter like and from/emailAddress/address eq 'email@example.com' there's a bug that the messages won't sort by the date so you always get the old messages first. Using the extended property fixed that issue but its a little weird.
$filter=SingleValueExtendedProperties/Any(ep: ep/PropertyId eq 'String 0x001a' and ep/Value eq 'IPM.SkypeTeams.Message') and and SingleValueExtendedProperties/Any(ep: ep/PropertyId eq 'String 0x5D01' and ep/Value eq 'firstname.lastname@example.org') One thing I did find after using this for a while is that it didn't work when I got a notification from teams like the following
Because the above notification message came from email@example.com it couldn't be used in the above query. Looking at the notification message unfortunately there wasn't any other properties that did contain the email address but the full DisplayName of the user was used in the email's displayName so as a quick workaround for these I made use of EWS's resolvename operation to resolve the displayName to an email address and then I could use the Addin even on the notification messages to see the private chat message that was sent to me within OWA without needing to open the Teams app (which if you have teams account in multiple tenants can be a real pain). So this one turned into a real productivity enhancer for me. (A quick note is that this will only get the Private Chat messages from the user not the Channel Messages).
Want to give it a try yourself ?
I've hosted the files on my GitHub pages so its easy to test (if you like it clone it and host it somewhere else). But all you need to do is add it as a custom addin (if your allowed to) using the
The GitHub repository for the Addin can be found here https://github.com/gscales/TeamsChatHistoryOWAAddIn