Classic ASP Requires Chilkat v11.0.0+
Imap.GetMailSize vs Email.Size

Shows how to get the total size of an email, as well as the sizes of the attachments. This can be done when either full-emails or headers-only are downloaded.
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Classic ASP
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
</head>
<body>
<%
success = 0

'  This example assumes the Chilkat API to have been previously unlocked.
'  See Global Unlock Sample for sample code.

set imap = Server.CreateObject("Chilkat.Imap")

'  Connect to an IMAP server.
'  Use TLS
imap.Ssl = 1
imap.Port = 993
success = imap.Connect("imap.example.com")
If (success = 0) Then
    Response.Write "<pre>" & Server.HTMLEncode( imap.LastErrorText) & "</pre>"
    Response.End
End If

'  Login
success = imap.Login("****","****")
If (success = 0) Then
    Response.Write "<pre>" & Server.HTMLEncode( imap.LastErrorText) & "</pre>"
    Response.End
End If

'  Select an IMAP mailbox
success = imap.SelectMailbox("Inbox")
If (success = 0) Then
    Response.Write "<pre>" & Server.HTMLEncode( imap.LastErrorText) & "</pre>"
    Response.End
End If

'  Get the message IDs of all the emails in the mailbox
'  We can choose to fetch UIDs or sequence numbers.
fetchUids = 1
set messageSet = Server.CreateObject("Chilkat.MessageSet")
success = imap.QueryMbx("ALL",fetchUids,messageSet)
If (success = 0) Then
    Response.Write "<pre>" & Server.HTMLEncode( imap.LastErrorText) & "</pre>"
    Response.End
End If

'  When downloading headers, each email object contains
'  (obviously) the headers, but the body will be missing.
'  Attachments will not be included.  However, it is
'  possible to get information about the attachments
'  as well as the complete size of the email.
set bundle = Server.CreateObject("Chilkat.EmailBundle")
headersOnly = 1
success = imap.FetchMsgSet(headersOnly,messageSet,bundle)
If (success = 0) Then
    Response.Write "<pre>" & Server.HTMLEncode( imap.LastErrorText) & "</pre>"
    Response.End
End If

'  Loop over the email objects and display information about each:
set email = Server.CreateObject("Chilkat.Email")
i = 0
j = 0
numEmails = bundle.MessageCount
Do While i < numEmails
    success = bundle.EmailAt(i,email)

    '  Display the From and Subject
    Response.Write "<pre>" & Server.HTMLEncode( email.From) & "</pre>"
    Response.Write "<pre>" & Server.HTMLEncode( email.Subject) & "</pre>"

    '  Display the recipients:
    j = 0
    Do While j < email.NumTo
        Response.Write "<pre>" & Server.HTMLEncode( "TO: " & email.GetToName(j) & ", " & email.GetToAddr(j)) & "</pre>"
        j = j + 1
    Loop
    j = 0
    Do While j < email.NumCC
        Response.Write "<pre>" & Server.HTMLEncode( "CC: " & email.GetCcName(j) & ", " & email.GetCcAddr(j)) & "</pre>"
        j = j + 1
    Loop

    '  Show the total size of the email, including body and attachments:
    Response.Write "<pre>" & Server.HTMLEncode( email.Size) & "</pre>"

    '  When a full email is downloaded, we would use the
    '  email.NumAttachments property in conjunction with the
    '  email.GetMailAttach* methods.
    '  However, when an email object contains only the header,
    '  we need to access the attachment info differently:
    numAttach = imap.GetMailNumAttach(email)
    j = 0
    Do While j < numAttach
        Response.Write "<pre>" & Server.HTMLEncode( imap.GetMailAttachFilename(email,j)) & "</pre>"
        attachSize = imap.GetMailAttachSize(email,j)
        Response.Write "<pre>" & Server.HTMLEncode( "    size = " & attachSize & " bytes") & "</pre>"
        j = j + 1
    Loop

    Response.Write "<pre>" & Server.HTMLEncode( "--") & "</pre>"

    i = i + 1
Loop

'  Disconnect from the IMAP server.
success = imap.Disconnect()

%>
</body>
</html>