Microsoft Outlook Interop (extract attachments) very slow

Question

I'm using Microsoft.Office.Interop.Outlook to extract e-mail attachments:

var MAPI = new Application().GetNamespace("MAPI");
var ExampleFolder = MAPI.GetDefaultFolder(OlDefaultFolders.olFolderSentMail)

foreach (dynamic i in ExampleFolder.Items)
  if (i.Attachments.Count > 0)
    ; // DoSomething();

Unfortunately this is extremely slow.

• Is there any faster way to check for attachments?
• Is it possible to filter/sort e-mails by date: loop through the last n items only?

Answer 1

@Kiquenet (I can't add a comment below yours), here is the code to get items with attachments from Items.Restrict:

//fanti's code
var MAPI = new Application().GetNamespace("MAPI");
var ExampleFolder = MAPI.GetDefaultFolder(OlDefaultFolders.olFolderSentMail)

• Urn way (tested, ok -> source https://social.msdn.microsoft.com/Forums/windowsapps/en-US/b6fef244-756c-4ab0-a22b-78137cfb4349/datereceived-filter-nor-happeinig?forum=outlookdev):

  var itemsWithAttachment = ExampleFolder.Items.Restrict("@SQL= urn:schemas:httpmail:hasattachment = True");
  

• DASL way (tested, ko -> 'should work' source https://learn.microsoft.com/en-us/office/client-developer/outlook/pia/how-to-filter-and-efficiently-enumerate-items-in-a-folder):

  const string PR_HAS_ATTACH = "https://schemas.microsoft.com/mapi/proptag/0x0E1B000B";
  var itemsWithAttachment = ExampleFolder.Items.Restrict("@SQL=\"" + PR_HAS_ATTACH + "\" = 1");
  

To filter by a date, just add "AND"s or "OR"s like this (Urn way):

var itemsWithAttachmentAndDate = ExampleFolder.Items.Restrict("@SQL= urn:schemas:httpmail:hasattachment = True"
 + " AND urn:schemas:httpmail:datereceived <= '" + DateTime.Now.AddMonths(-3) + "'");

To loop through the last n items only:

int n = 3;
for (int i = itemsWithAttachmentAndDate.Count - 1; i > n; i--)
{
    //current item: itemsWithAttachmentAndDate[i] //Beware: "dynamic" typed!
    ; //DoSomething();
}

Answer 2

sure, you can sort the collection using Items.Sort. You can also use Items.Find/FindNext or Items.Restrict to look for items with attachments only. The property you need is PR_HASATTACH (DASL name http://schemas.microsoft.com/mapi/proptag/0x0E1B000B)