How do you extract email addresses from the 'To' field in outlook?

It looks like, for email addresses outside of your organization, the SMTP address is hidden in emailObject.Recipients(i).Address, though it doesn't seem to allow you to distinguish To/CC/BCC.

The Microsoft code was giving me an error, and some investigating reveals that the schema page is no longer available. I wanted a semicolon-delaminated list of email addresses that were either in my Exchange organization or outside of it. Combining it with another S/O answer to convert inner-company email display names to SMTP names, this does the trick.

Function getRecepientEmailAddress(eml As Variant)
    Set out = CreateObject("System.Collections.Arraylist") ' a JavaScript-y array

    For Each emlAddr In eml.Recipients
        If Left(emlAddr.Address, 1) = "/" Then
            ' it's an Exchange email address... resolve it to an SMTP email address
            out.Add ResolveDisplayNameToSMTP(emlAddr)
        Else
            out.Add emlAddr.Address
        End If
    Next
    getRecepientEmailAddres = Join(out.ToArray(), ";")
End Function

If the email is inside your organization, you need to convert it to an SMTP email address. I found this function from another StackOverflow answer helpful:

Function ResolveDisplayNameToSMTP(sFromName) As String
    ' takes a Display Name (i.e. "James Smith") and turns it into an email address ([email protected])
    ' necessary because the Outlook address is a long, convoluted string when the email is going to someone in the organization. 
    ' source:  https://stackoverflow.com/questions/31161726/creating-a-check-names-button-in-excel

    Dim OLApp As Object 'Outlook.Application
    Dim oRecip As Object 'Outlook.Recipient
    Dim oEU As Object 'Outlook.ExchangeUser
    Dim oEDL As Object 'Outlook.ExchangeDistributionList

    Set OLApp = CreateObject("Outlook.Application")
    Set oRecip = OLApp.Session.CreateRecipient(sFromName)
    oRecip.Resolve
    If oRecip.Resolved Then
        Select Case oRecip.AddressEntry.AddressEntryUserType
            Case 0, 5 'olExchangeUserAddressEntry & olExchangeRemoteUserAddressEntry
                Set oEU = oRecip.AddressEntry.GetExchangeUser
                If Not (oEU Is Nothing) Then
                    ResolveDisplayNameToSMTP = oEU.PrimarySmtpAddress
                End If
            Case 10, 30 'olOutlookContactAddressEntry & 'olSmtpAddressEntry
                    ResolveDisplayNameToSMTP = oRecip.AddressEntry.Address
        End Select
    End If
End Function

Check out the Recipients collection object for your mail item, which should allow you to get the address: http://msdn.microsoft.com/en-us/library/office/ff868695.aspx

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Update 8/10/2017

Looking back on this answer, I realized I did a bad thing by only linking somewhere and not providing a bit more info.

Here's a code snippet from that MSDN link above, showing how the Recipients object can be used to get an email address (snippet is in VBA):

Sub GetSMTPAddressForRecipients(mail As Outlook.MailItem) 
    Dim recips As Outlook.Recipients 
    Dim recip As Outlook.Recipient 
    Dim pa As Outlook.PropertyAccessor 
    Const PR_SMTP_ADDRESS As String = _ 
        "http://schemas.microsoft.com/mapi/proptag/0x39FE001E" 
    Set recips = mail.Recipients 
    For Each recip In recips 
        Set pa = recip.PropertyAccessor 
        Debug.Print recip.name &; " SMTP=" _ 
           &; pa.GetProperty(PR_SMTP_ADDRESS) 
    Next 
End Sub