Emails can be sent from various places within the system. See this article to learn more.
When you choose your method of sending an email message you will encounter the Email Builder Client pop-out (see below) which allows you to draft your email and decide on other sending options.
The first section allows you to decide who this email is from. It will default to the email address of the person who is drafting the email but you can change who the email is from by selecting the dropdown and choosing "From your organization".
Or, by selecting the red "X" and choosing another person within the system.
This section allows you to indicate the recipient or recipients of the email.
Select the arrow to choose between a "person" or "group" search.
Section three is the text editor which is were you draft the email or insert an email template.
This section allows you to add attachments, up to 7mbs and only allows for a single attachment.
Select the blue "Add Attachment" link to add your attachment.
NOTE: You can only send one attachment. If you need to send more than one file, the recommended approach is to use the document library and include links in the email. The following file types are allowed: txt, pdf, png, jpg, doc, docx, xls, xlsx, zip
Here you choose to send the email Now or Later by scheduling a specific date & time in the future to send your email.
Select the "Later" radio button > choose your date & time > select "Schedule Email".
NOTE: Feature NOT available on Standard Plan
This section also allows you to send yourself a "test email" before you send the email to the list.