SMTP Handler - Attachments empty

[m4admin]

Bug: SMTP $SmtpEvent.Email.Attachments empty/zero bytes while raw $SmtpEvent.Email.Data contains attachments (MimeKit can extract)

Summary

When receiving emails via Pode SMTP, $SmtpEvent.Email.Attachments is empty or contains attachments with Bytes.Length = 0, even though the raw message in $SmtpEvent.Email.Data clearly contains the MIME attachment parts. If I parse $SmtpEvent.Email.Data using MimeKit, the attachments are present and can be extracted with correct sizes.

This makes attachment forwarding/processing unreliable unless I re-parse the raw MIME message myself.

Environment

• Pode: 2.12.1
• PowerShell: 7.4.13

Expected behavior

• $SmtpEvent.Email.Attachments contains all attachments present in the email, with non-empty Bytes matching the actual attachment content.

Actual behavior

• $SmtpEvent.Email.Attachments is empty

Reproduction steps

1. Start a Pode SMTP server with a handler that logs attachment info and saves raw message data.
2. Send an email with one or more attachments (e.g., PDF, DOCX, PNG) from Outlook/Exchange.
3. Observe that $SmtpEvent.Email.Attachments is empty or has zero-length bytes.
4. Parse $SmtpEvent.Email.Data with MimeKit and confirm attachments exist and can be extracted.

[Badgerati]

Hi @m4admin,

Would you be able to provide an example of an SMTP Request - Headers/Body - that isn't parsing as expected?

I've just tried myself with various and multiple attachments, and they are always populated in $SmtpEvent.Email.Attachments.

I suspect this might be something Outlook itself is causing, and I don't have it to test.

[m4admin]

Tested with this code:

$to = "helpdesk@firma.tld"
$from = "test@test.de"
$subject = "test"

# Konfiguration
$smtpServer = "smtp"

# MailMessage
$mail = New-Object System.Net.Mail.MailMessage
$mail.From = $From
$mail.To.Add($To)
$mail.Subject = $Subject
$mail.IsBodyHtml = $true

$htmlbody = "<b>test</b>"

# AlternateView (HTML)
$view = [System.Net.Mail.AlternateView]::CreateAlternateViewFromString(
    $HtmlBody,
    $null,
    "text/html"
)
$mail.AlternateViews.Add($view)

# === Attachment  ===
$filePath = "C:\Temp\Test.pdf"

if (Test-Path $filePath) {
    $attachment = New-Object System.Net.Mail.Attachment($filePath)
    $mail.Attachments.Add($attachment)
}

# SMTP 
$smtp = New-Object System.Net.Mail.SmtpClient($smtpServer)
$smtp.Send($mail)
$mail.Dispose()

[Badgerati]

Hi @m4admin,

Thanks for the snippet, with that I can reproduce the missing attachments. The issue is down the Pode not currently supporting Alternative Views and multiple boundaries in SMTP requests.

You can see in the below examples the embedded boundaries. The top one is from your snippet above, and the bottom is what normal simple SMTP requests look like (what Pode is currently built to handle).

I can look to get this added; will change this from bug to enhancement.

• SMTP request from your snippet:

MIME-Version: 1.0
From: test@test.de
To: helpdesk@firma.tld
Date: 22 Apr 2026 20:40:52 +0100
Subject: test
Content-Type: multipart/mixed;
 boundary=--boundary_1_8b73c5fc-9031-4cca-9d45-77f9e5862591


----boundary_1_8b73c5fc-9031-4cca-9d45-77f9e5862591
Content-Type: multipart/alternative;
 boundary=--boundary_0_a8f9ac42-c7ce-4a97-88f4-c9ebfe9a7b63


----boundary_0_a8f9ac42-c7ce-4a97-88f4-c9ebfe9a7b63
Content-Type: text/html; charset=us-ascii
Content-Transfer-Encoding: quoted-printable

<b>test</b>
----boundary_0_a8f9ac42-c7ce-4a97-88f4-c9ebfe9a7b63--

----boundary_1_8b73c5fc-9031-4cca-9d45-77f9e5862591
Content-Type: multipart/mixed;
 boundary=--boundary_2_5297fe67-04ed-4b24-a62e-eef269349945


----boundary_2_5297fe67-04ed-4b24-a62e-eef269349945
Content-Type: application/octet-stream; name=Ruler.png
Content-Transfer-Encoding: base64
Content-Disposition: attachment

iVBORw0KGgoAAAANSUhEUgAAADAAAAAwCAYAAABXAv ... RK5CYII=
----boundary_2_5297fe67-04ed-4b24-a62e-eef269349945--

----boundary_1_8b73c5fc-9031-4cca-9d45-77f9e5862591--


.

• Simple SMTP requests:

MIME-Version: 1.0
From: test@test.de
To: helpdesk@firma.tld
Date: 22 Apr 2026 20:42:50 +0100
Subject: test
Content-Type: multipart/mixed;
 boundary=--boundary_0_c7b5b4ba-deb1-4e85-8ab2-6f8c8c5b24ae


----boundary_0_c7b5b4ba-deb1-4e85-8ab2-6f8c8c5b24ae
Content-Type: text/html; charset=us-ascii
Content-Transfer-Encoding: quoted-printable

<b>test</b>
----boundary_0_c7b5b4ba-deb1-4e85-8ab2-6f8c8c5b24ae
Content-Type: application/octet-stream; name=Ruler.png
Content-Transfer-Encoding: base64
Content-Disposition: attachment

iVBORw0KGgoAAAANSUhEUgAAADAAAAAwCAYAAABXAv ... RK5CYII=
----boundary_0_c7b5b4ba-deb1-4e85-8ab2-6f8c8c5b24ae--


.