"type mismatch: array or user defined type expected" on compile from this stmt:
SendMail = MAPISendMail(Session, 0&, Msg, recip(0), Files(0), 0&, 0&)

It doesn't like recip(0)

Here's the function within a class:
Public Function SendMail() As Long

Dim Msg As MAPIMessage
ReDim recip(0) As MapiRecip
ReDim Files(0) As MapiFile
If Recipients.Count Then
RecipToArray recip()
Else
Exit Function
End If
Msg.RecipCount = Recipients.Count
If Attachments.Count Then
AttachToArray Files()
End If
Msg.FileCount = Attachments.Count
Msg.Reserved = 0&
Msg.Subject = Subject
Msg.NoteText = Space$(Msg.FileCount + 5) & NoteText
Msg.MessageType = MessageType
Msg.DateReceived = ""
Msg.ConversationID = ""
Msg.Flags = 0&
SendMail = MAPISendMail(Session, 0&, Msg, recip(0), Files(0), 0&, 0&)
End Function


MapiRecip is defined as a public type in a bas module

Public Type MapiRecip
Reserved As Long
RecipClass As Long
Name As String
Address As String
EIDSize As Long
EntryID As String
End Type

And this is the mapi api for sendmail

Declare Function MAPISendMail Lib "MAPI32.DLL" Alias "BMAPISendMail" (ByVal Session&, ByVal UIParam&, Message As MAPIMessage, Recipient() As MapiRecip, File() As MapiFile, ByVal Flags&, ByVal Reserved&) As Long