Graph_Teams_channel_SMTP.ps1

#Requires -Version 3.0
# Make sure to fill in all the required variables before running the script
# Also make sure the AppID used corresponds to an app with sufficient permissions, as follows:
#    Group.Read.All or Directory.Read.All to read all Groups
#    Group.Read.All to read Channel info

#Variables to configure

$tenantID = "tenant.onmicrosoft.com" #your tenantID or tenant root domain
$appID = "xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx" #the GUID of your app.
$client_secret = "verylongsecurestring" #client secret for the app

#==========================================================================
#Main script starts here
#==========================================================================

#Obtain access token
$url = 'https://login.microsoftonline.com/' + $tenantId + '/oauth2/v2.0/token'

$Scopes = New-Object System.Collections.Generic.List[string]
$Scope = "https://graph.microsoft.com/.default"
$Scopes.Add($Scope)

$body = @{
    grant_type = "client_credentials"
    client_id = $appID
    client_secret = $client_secret
    scope = $Scopes
}

try {
    Set-Variable -Name authenticationResult -Scope Global -Value (Invoke-WebRequest -Method Post -Uri $url -Debug -Verbose -Body $body)
    $token = ($authenticationResult.Content | ConvertFrom-Json).access_token
}
catch { $_; return }

if (!$token) { Write-Host "Failed to aquire token!"; return }
else {
    Write-Verbose "Successfully acquired Access Token"

    #Use the access token to set the authentication header
    Set-Variable -Name authHeader -Scope Global -Value @{'Authorization'="Bearer $token";'Content-Type'='application\json'}
}

#Use the /beta endpoint to fetch a list of all Teams
#Do not switch to https://graph.microsoft.com/beta/teams as we need the Group proxy address details
$uri = "https://graph.microsoft.com/beta/groups?`$filter=resourceProvisioningOptions/Any(x:x eq `'Team`')&`$select=id,displayName,mail,proxyAddresses,resourceBehaviorOptions,resourceProvisioningOptions,visibility"
$result = Invoke-WebRequest -Headers $AuthHeader -Uri $uri -Verbose:$VerbosePreference
$teams = ($result.Content | ConvertFrom-Json).Value

#iterate over each Team and gather channel information
$output = @()
foreach ($team in $teams) {
    $uri = "https://graph.microsoft.com/v1.0/teams/$($team.id)/channels"
    $result = Invoke-WebRequest -Headers $AuthHeader -Uri $uri -Verbose:$VerbosePreference
    $channels = ($result.Content | ConvertFrom-Json).Value

    #$channels | select displayName,email,id,webUrl
    foreach ($channel in $channels) {
        $chaninfo = New-Object psobject
        $chaninfo | Add-Member -MemberType NoteProperty -Name "Id" -Value $channel.id
        $chaninfo | Add-Member -MemberType NoteProperty -Name "Team" -Value $team.displayName
        $chaninfo | Add-Member -MemberType NoteProperty -Name "TeamId" -Value $team.id
        $chaninfo | Add-Member -MemberType NoteProperty -Name "TeamEmailAddresses" -Value $($team.proxyAddresses -join ",")
        $chaninfo | Add-Member -MemberType NoteProperty -Name "Visibility" -Value $team.visibility
        $chaninfo | Add-Member -MemberType NoteProperty -Name "Channel" -Value $channel.displayName
        $chaninfo | Add-Member -MemberType NoteProperty -Name "ChannelEmail" -Value (&{If($channel.email) {$channel.email} Else {"N/A"}})
        $output += $chaninfo
    }

}

#return the output
$global:varTeamChannels = $output | select Team,Visibility,Channel,ChannelEmail,TeamEmailAddresses,TeamId
#$output | select * | Export-Csv -Path "$((Get-Date).ToString('yyyy-MM-dd_HH-mm-ss'))_TeamsChannels.csv" -NoTypeInformation -Encoding UTF8 -UseCulture
return $global:varTeamChannels