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<#
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Name : Configure External Email Warning Message for External Office 365 Emails
Version : 3.0
Website : o365reports . com
Script Highlights :
~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~
1 . This script can be executed with MFA enabled account too .
2 . Prepends “ External ” to subject line for incoming external emails
3 . Adds “ External Disclaimer ” for external emails
4 . You can exclude group mailboxes like support , sales that facing external world .
For detailed script execution : https : / / o365reports . com / 2020 / 03 / 25 / how-to -add -external -email -warning -message /
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#>
#Create mail flow rule for adding External warning message for external mails
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Param
(
[ Parameter ( Mandatory = $false ) ]
[ string ] $ExcludeGroupMembers ,
[ string ] $ExcludeMB ,
[ string ] $UserName ,
[ string ] $Password
)
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#Check for EXO module inatallation
$Module = Get-Module ExchangeOnlineManagement -ListAvailable
if ( $Module . count -eq 0 )
{
Write-Host Exchange Online PowerShell module is not available -ForegroundColor yellow
$Confirm = Read-Host Are you sure you want to install module ? [ Y] Yes [N ] No
if ( $Confirm -match " [yY] " )
{
Write-host " Installing Exchange Online PowerShell module "
Install-Module ExchangeOnlineManagement -Repository PSGallery -AllowClobber -Force
Import-Module ExchangeOnlineManagement
}
else
{
Write-Host EXO module is required to connect Exchange Online . Please install module using Install-Module ExchangeOnlineManagement cmdlet .
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Exit
}
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}
Write-Host Connecting to Exchange Online . . .
#Storing credential in script for scheduling purpose/ Passing credential as parameter - Authentication using non-MFA account
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if ( ( $UserName -ne " " ) -and ( $Password -ne " " ) )
{
$SecuredPassword = ConvertTo-SecureString -AsPlainText $Password -Force
$Credential = New-Object System . Management . Automation . PSCredential $UserName , $SecuredPassword
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Connect-ExchangeOnline -Credential $Credential
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}
else
{
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Connect-ExchangeOnline
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}
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$Disclaimer = '<p><div style="background-color:#FFEB9C; width:100%; border-style: solid; border-color:#9C6500; border-width:1pt; padding:2pt; font-size:10pt; line-height:12pt; font-family:Calibri; color:Black; text-align: left;"><span style="color:#9C6500"; font-weight:bold;>CAUTION:</span> This email originated from outside of the organization. Do not click links or open attachments unless you recognize the sender and know the content is safe.</div><br></p>'
$ExcludeGroups = @ ( )
$ExcludeMBs = @ ( )
#Check for exclude groups
if ( [ string ] $ExcludeGroupMembers -ne " " )
{
$Groups = $ExcludeGroupMembers -Split " , "
#Check whether the grup exists
foreach ( $Group in $Groups )
{
$check = Get-DistributionGroup -Identity $Group -ErrorAction SilentlyContinue
if ( $check -eq $null )
{
$check = Get-UnifiedGroup -Identity $Group -ErrorAction silentlycontinue
if ( $check -eq $null )
{
Write-Host $Group not exist in the tenant -ForegroundColor Red
continue
}
}
$ExcludeGroups + = $Group
}
Write-Host ` nCreating mail flow rule for External Senders . . . -ForegroundColor Yellow
New-TransportRule " External Email Warning " -FromScope NotInOrganization -SentToScope InOrganization -PrependSubject [ EXTERNAL ] : -Priority 0 -ApplyHtmlDisclaimerText $Disclaimer -ExceptIfSentToMemberOf $ExcludeGroups -ApplyHtmlDisclaimerLocation Prepend -ApplyHtmlDisclaimerFallbackAction Wrap
}
#Create Transport rule with exclude mailbox that in To and CC
elseif ( $ExcludeMB -ne " " )
{
$MBs = $ExcludeMB -Split " , "
#Check whether the grup exists
foreach ( $MB in $MBs )
{
$ExcludeMBs + = $MB
}
Write-Host ` nCreating mail flow rule for External Senders . . . -ForegroundColor Yellow
New-TransportRule " External Email Warning " -FromScope NotInOrganization -SentToScope InOrganization -PrependSubject [ EXTERNAL ] : -Priority 0 -ApplyHtmlDisclaimerText $Disclaimer -ExceptIfAnyOfToCCHeader $ExcludeMBs -ApplyHtmlDisclaimerLocation Prepend -ApplyHtmlDisclaimerFallbackAction Wrap
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}
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else
{
Write-Host Creating mail flow rule for External Senders . . . -ForegroundColor Yellow
New-TransportRule " External Email Warning " -FromScope NotInOrganization -SentToScope InOrganization -PrependSubject [ EXTERNAL ] : -Priority 0 -ApplyHtmlDisclaimerText $Disclaimer -ApplyHtmlDisclaimerLocation Prepend -ApplyHtmlDisclaimerFallbackAction Wrap
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}
Write-Host ` n ~ ~ Script prepared by AdminDroid Community ~ ~ ` n -ForegroundColor Green
Write-Host " ~~ Check out " -NoNewline -ForegroundColor Green ; Write-Host " admindroid.com " -ForegroundColor Yellow -NoNewline ; Write-Host " to get access to 1800+ Microsoft 365 reports. ~~ " -ForegroundColor Green ` n ` n
Disconnect-ExchangeOnline
