iCloud: Send email using a web browser
Using iCloud Mail, you can compose and send email using a Mac or Windows web browser. For recommended browsers, see the Apple Support article iCloud: System requirements.
Compose and send messages using iCloud Mail
Click the Compose button.
Type one or more names or email addresses in an address field. If addresses don’t appear enclosed in blue fields, separate them with commas.
iCloud Mail tries to complete addresses as you type them, based on addresses in iCloud Contacts or recipients that you previously emailed. If iCloud Mail finds more than one match, it displays a list of addresses that match what you typed so far. To use one of the suggested addresses, select it, then press Return. iCloud Mail encloses the address in a blue field.
To view all of your contacts, click the Add button in the upper-right corner of the New Message window.
In the Subject field, type a subject for the email.
If you want to send the message from an address you don’t usually use, choose an address from the From pop-up menu.
You have multiple addresses if you created an email alias or you have an @me.com or @mac.com address in addition to your @icloud.com address.
Type your message, then click the Send button in the upper-right corner of the New Message window.