By attaching a mailbox, you automatically get the option to use the address of the connected account as the sender's address.
When writing a message, click on the arrow after the sender's address (1.) (the presence of other addresses is indicated by this arrow) and select the desired address from the list (2.).
When replying or forwarding an email, the sender's address is used automatically depending on which mailbox you are in.
Trouble logging in? Simply enter your email address OR username in order to reset your password.
For faster and more reliable delivery, add email@example.com to your trusted senders list in your email software.