Mass emails from distribution list with same subject line

Is there a way to open all distribtion lists selected and have the same subject line inserted?

Daily I send 100 emails with the same subject line but different attachments to different distribution lists, looking for a way to shorten my process, currently I open all lists and copy paste the subject line then attach document. Is there any way to cut out the paste step?

yes there is, but you didn't provide any details.