Currently, the user has to activate the transactional mails by clicking "start" button for each individual mail, and if there are mails that haven't been activated, there will be a dialogue showing up to list out the to-dos before the MA campaign can be started (see screenshot)

As a marketing campaign manager, I want to be able to bulk starting(activating) the transactional mails.

possible solutions:

1. Provide option in transactional mails overview to multi-select
2. When starting the Marketing Automation campaign, a dialogue shows up if there are not-activated transactional mails (maybe with a list of the mailings) to ask the user if they want those to be automatically activated, if the user chooses yes, all not-activated transactional mails in the MA campaign will be activated so the user does not have to go back to go through the overview list.

Minor improvement: We could change the wording "start" in transactional mails overview to avoid potential confusion (e.g. activate), especially for the new users.