From 422583d0f4fc9e98a5255df65c1d0cf9bd35e45e Mon Sep 17 00:00:00 2001
From: kirkH <kirk@passivelogic.com>
Date: Thu, 6 Jun 2024 10:52:11 -0600
Subject: [PATCH] feat: contentID for email attachments

---
 Sources/Smtp/Models/Attachment.swift | 4 +++-
 Sources/Smtp/Models/Email.swift      | 3 +++
 2 files changed, 6 insertions(+), 1 deletion(-)

diff --git a/Sources/Smtp/Models/Attachment.swift b/Sources/Smtp/Models/Attachment.swift
index 01af71b..cfcaa07 100644
--- a/Sources/Smtp/Models/Attachment.swift
+++ b/Sources/Smtp/Models/Attachment.swift
@@ -10,10 +10,12 @@ public struct Attachment {
     public let name: String
     public let contentType: String
     public let data: Data
+    public let contentID: String?
 
-    public init(name: String, contentType: String, data: Data) {
+    public init(name: String, contentType: String, data: Data,  contentID: String? = nil) {
         self.name = name
         self.contentType = contentType
         self.data = data
+        self.contentID = contentID
     }
 }
diff --git a/Sources/Smtp/Models/Email.swift b/Sources/Smtp/Models/Email.swift
index 0200af2..f77314e 100644
--- a/Sources/Smtp/Models/Email.swift
+++ b/Sources/Smtp/Models/Email.swift
@@ -122,6 +122,9 @@ extension Email {
             for (index, attachment) in self.attachments.enumerated() {
                 out.writeString("Content-type: \(attachment.contentType)\r\n")
                 out.writeString("Content-Transfer-Encoding: base64\r\n")
+                if let contentID = attachment.contentID  {
+                    out.writeString("Content-ID: \(contentID)\r\n")
+                }
                 out.writeString("Content-Disposition: attachment; filename=\"\(attachment.name)\"\r\n\r\n")
                 out.writeString("\(attachment.data.base64EncodedString())\r\n")