It is pretty simple. For you concatenation string for the To field, before to delimit the values with semicolons.
e.g.
'More Excel to Outlook Examples: http://www.rondebruin.nl/win/s1/outlook/bmail4.htm
'http://www.rondebruin.nl/win/s1/outlook/signature.htm
'Add reference: Microsoft Outlook xx.x Library, where xx.x is 14.0, 15.0, 16.0, etc.
Sub Main()
Dim olApp As Outlook.Application, olMail As Outlook.MailItem
Dim a() As Variant, r As Range, c As Range
Set olApp = New Outlook.Application
Set r = Range("B2", Range("B" & Rows.Count).End(xlUp))
For Each c In r
Set olMail = olApp.CreateItem(olMailItem)
With olMail
.To = c.Value 'Column B
.Subject = "Pin No. " & c.Offset(, 3) 'Column E
.Body = c.Offset(, 1) 'Column C
.Display
'.Send
Exit Sub
End With
Next c
Set olMail = Nothing
Set olApp = Nothing
End Sub