Outlook VBA-Macro for to check mails concerning recipients and attachments
For multiple address, why not have a collection of emails?

Public Function GetSendToList () As Collection

    Dim emailList As Collection
    Set emailList = New Collection

    emailList.Add "main.clerk@smth.com"
    emailList.Add "deputy.clerk@smth.com"
    emailList.Add etc.

    Set GetSendToList = emailList

End Function


And then:

Dim emailList as Collection
Set emailList = GetSendToList

...
...
...

For i = 1 to emailList.Count
    emailToCheck = emailList(i)
    '/ code to check the email against your message
Next i


This means that you can:


Keep your hard-coded list away from your business logic, making both 
cleaner and easier to find
Have just one place you go to to add/remove emails from your list, rather than wading through a sub to find it.
Have just one (validate email) loop, so you don't have to repeat your code for each one.


In my projects, I often have a separate module for "Manually-Set Values" but that's just personal preference.