使用SentOnBehalfOfName/共享邮箱时Outlook Interop的SaveSentMessageFolder失效

问题背景 #

用PowerShell结合Microsoft.Office.Interop.Outlook通过本地Outlook自动发邮件，因组织限制无法使用SMTP（无应用密码）或Microsoft Graph的Mail.Send接口，只能采用此方案。代码中已正确设置SaveSentMessageFolder指向共享邮箱的“Sent Items”，但发送后邮件仍存入个人账号的已发送文件夹，调试确认路径设置无误：

[DEBUG] pre: \me@example.com\Sent Items
[DEBUG] post: \SentOnBehalfOfName Display Name\Sent Items
[DEBUG] just before send: \SentOnBehalfOfName Display Name\Sent Items

原代码如下：

Add-Type -assembly "Microsoft.Office.Interop.Outlook"
Add-Type -assembly "System.Runtime.Interopservices"

$oClient = [Runtime.Interopservices.Marshal]::GetActiveObject('Outlook.Application')
$oNamespace = $oClient.GetNamespace("MAPI")

$sharedFolder = $oClient.Session.Folders | Where-Object -Property Name -eq -Value "<Shared Mailbox Name>"
$sharedSentFolder = $sharedFolder.Folders | Where-Object -Property Name -eq -Value "Sent Items"

function Send-OutlookEmail {

    [CmdletBinding()]
    param (
        [Parameter(Mandatory)]
        $OutlookClient,

        [Parameter(Mandatory)]
        $OutlookNamespace,

        [Parameter(Mandatory)]
        [string]$Recipient,

        [string[]]$CC,

        [string[]]$BCC,

        [Parameter(Mandatory)]
        [string]$Subject,

        [Parameter(Mandatory)]
        [string]$HTMLBody,

        [bool]$ReadReceipt = $false,

        [int]$Priority = 1,

        [string]$SendFromAddress,

        $SentMessageFolder
    )

    $email = $OutlookClient.CreateItem(0) # OlItemType.olMailItem

    $rcp = $email.Recipients.Add($Recipient)
    $rcp.Type = 1

    $email.Subject = $Subject
    $email.BodyFormat = 2 # OlBodyFormat.olFormatHTML
    $email.HTMLBody = $HTMLBody

    $email.ReadReceiptRequested = $ReadReceipt
    $email.Importance = $Priority

    if ($CC) {
        foreach ($cc in $CC) {
            $r = $email.Recipients.Add($cc)
            $r.Type = 2 # CC (OlMailRecipientType.olCC)
        }
    }

    if ($BCC) {
        foreach ($bcc in $BCC) {
            $r = $email.Recipients.Add($bcc)
            $r.Type = 3 # BCC (OlMailRecipientType.olBCC)
        }
    }

    if ($SendFromAddress) {
        $email.SentOnBehalfOfName = $SendFromAddress
    }

    if ($SentMessageFolder -and $OutlookNamespace) {
        $sf = $oNamespace.GetFolderFromID($SentMessageFolder.EntryID, $SentMessageFolder.StoreID)

        $email.SaveSentMessageFolder = $sf
    }

    try {
        # Send the email
        $email.Send()
    } catch {
        Write-Host "Error sending email to " $Recipient "!"
    }
}

Send-OutlookEmail `
    -OutlookClient $oClient `
    -OutlookNamespace $oNamespace `
    -SendFromAddress "mysharedmailbox@example.com" `
    -SentMessageFolder $sharedSentFolder `
    -Recipient "me@example.com" `
    -Subject "This is a test email" `
    -HTMLBody "<html><body><p>Hello there.</p></body></html>"

解决方案 #

1. 从共享邮箱草稿文件夹创建邮件（推荐） #

直接在共享邮箱的“草稿”文件夹创建邮件，让邮件归属共享邮箱上下文，发送后会自动存入对应已发送文件夹，无需额外设置SaveSentMessageFolder：

修改函数内创建邮件的代码：

# 替换原 $email = $OutlookClient.CreateItem(0)
$sharedDraftsFolder = $sharedFolder.Folders | Where-Object Name -eq "Drafts"
$email = $sharedDraftsFolder.Items.Add()

2. 使用SendUsingAccount替代SentOnBehalfOfName #

确保你的账号拥有共享邮箱的Send As权限（而非仅Send On Behalf Of），然后用SendUsingAccount指定发送账号，替代SentOnBehalfOfName：

# 替换原 $email.SentOnBehalfOfName = $SendFromAddress
$sendAccount = $OutlookNamespace.Accounts | Where-Object DisplayName -eq $SendFromAddress
if ($sendAccount) {
    $email.SendUsingAccount = $sendAccount
}

3. 发送后手动移动邮件（备选） #

如果上述方法无效，可在发送后将个人已发送文件夹中的对应邮件移动到共享邮箱的已发送文件夹：

try {
    $email.Send()
    # 查找刚发送的邮件并移动
    $personalSentItems = $OutlookNamespace.GetDefaultFolder(5) # olFolderSentMail
    $targetEmail = $personalSentItems.Items | Where-Object { 
        $_.Subject -eq $Subject -and 
        $_.SentOn -ge (Get-Date).AddMinutes(-1) 
    } | Select-Object -First 1
    if ($targetEmail) {
        $targetEmail.Move($sharedSentFolder)
    }
} catch {
    Write-Host "Error sending email to " $Recipient "!"
}

原因分析 #

• 用CreateItem创建的邮件默认属于当前登录的个人邮箱上下文，Outlook的组织策略或权限设置可能会覆盖SaveSentMessageFolder配置，强制存入个人已发送文件夹。
• 从共享邮箱草稿文件夹创建邮件，邮件的存储上下文直接关联共享邮箱，发送后会遵循共享邮箱的存储规则。

内容的提问来源于stack exchange，提问作者Ralph