如何根据按下的按钮填充电子邮件收件人？

I have an app that is for 3 different offices and I would like to be able to choose which office the resulting collated data will be sent to via an email. I would like to use a different button for each of the offices that will automatically populate an email recipient and then a final button at the end will collate all the information and attach it all to an email. Is there any way of doing this? I have the send button figured out, its the populating the recipient that I can't work out.I have an app that is for 3 different offices a