Adding another list to an already sent list?

[Terskac]

I sent out an email last week that seems to have turned out well. I would like to add more lists to this mailing. I am sure there are duplicates in the lists. Is there a way to add more lists to the already sent mailing so I can prevent duplicates?

 

[stanbusk]

This is done automatically as long as the duplicate checking is activated in your preferences.

 

[Terskac]

But

I figured it out. Select new list, multiple then choose the list I already did first. Select them all and mark them as sent. Then add more lists.