How to Send Mail From a Different Account in iOS Mail
The Mail app in the iPhone iOS sends and receives emails from as many accounts as you have on the phone. After you configure a second (or subsequent) email account, you unlock the functionality to specify the outgoing account for a given message. To choose the account from which the email or reply you are composing in iPhone Mail will be sent:
How to Use Several Accounts in iOS Mail
When you change the From a line of an outgoing message, you also change the account from which the message is sent. For example, if you set up an iCloud account and a Gmail account on your iPhone, and you switch from one account to the other when you send a message, the outgoing message appears in that account’s Sent Mail folder, and replies are delivered to the inbox of the account that sent it. In other words, you’re changing the account, not merely the address, that governs that particular message.
