Can you show me where to activate ?
This link should help. By default, the initial installation of DEVONthink should have activated the menu.
Thanks for your help and link. I have checked but the Script Editor was already activated.
I still don’t see it in the Menu
Do you use a menu utility like Bartender that may have hidden the script menu?
Just to be clear, this is a different, global script menu that appears on the right side of the menu (what Jim posted above). The commands do not appear in the DEVONthink script menu that you posted a screen cap of.
This is what I see
Did you install the scripts via DEVONthink 3 > Install Add-Ons…? In addition, Outlook has to be the active application.
Now finally I see it : if I have Outlook as the active application, the script appears
Thanks 
After running the script they still appear in the inbox. My idea was to get them straight into the archive (see my initial question).
So the question remains : what is the best way to build and to keep an Outlook e-mail archive updated in DTPO ? What is the best rule to follow ?
Using Archive Mailbox again will update the existing archive and skip already imported messages.
Thanks, but why I still see the messages appear in the Inbox after using " Archive Mailbox " ?
Do I need to move them manually ?
Which destination is selected (see popup in the right sidebar of the email interface)? Email archiving remembers the last used destination.
Ah… I see it, yes Inbox. I have changed it now to the correct destination.
Wow, what an options are there possible !
Thanks everyone for your help !
Sorry to ask one more thing regarding this :
What is the difference between Mailbox and Messages ?
Is Messages if you already have imported the first time the complete data from Outlook and want to update is with the latest e-mail since last import ?
I would use the Messages option with selected messages as adding the Mailbox via the script will generate duplicates.
And with Messages the script will put the e-mail in the correct folders ?
Will Mailbox duplicates show up ?
And with Messages the script will put the e-mail in the correct folders ?
Only if you use the group selector.
Will Mailbox duplicates show up ?
Yes. They will show a split rectangle icon to the right of the name or appear in blue if Preferences > General > Appearance > Mark duplicates and replicants in color is enabled.
How do I use the group selector ?
Enable Preferences > Import > Destination > Select group and you’ll see the group selector.
Will it import all the folders like Inbox, Send, Trash etc ? Or only the selected messages in Outlook and using the script ?
“Add message(s) to DEVONthink” imports the selected messages, “Add mailbox(es) to DEVONthink” the selected mailboxes.