Send email to users in a list from Lookup activity

There are 3 ways :

1) you can semi colon seperate the recipients within the warehouse while executing the lookup activity

2) pass the value of lookup activity to a for each activity. within for each activity,use set variable activity to append the iterations in a semi colon manner

or 3) expression :

https://stackoverflow.com/questions/58632744/adf-expression-to-convert-array-to-comma-separated-string

Hi amaaiia 
Thanks for using Fabric Community.
Please refer to this link:
Microsoft Fabric - Pipelines - Parse Multiple Email Addresses for the Office 365 Outlook Activity (youtube.com)

Hope this helps. Please let me know if you have any other questions.