If you have users added to your 17hats account, you will be unable to connect Office365 as your Outgoing Server. Office365 requires the account email to match the "email sent as" address. When using your own server, the address showing the message as sent will always be the outgoing server email address. Because each user will not have the same email address as the outgoing server, you will need to use the 17hats server instead.
When you send a message with the 17hats server, it will show as being sent from the address listed in the "Email Sent As" Address section. This is shown in your Outgoing email settings and is set by the address listed in your Account Setting.
When the message is sent, it will show the senders name, their email address that is listed in account settings, and the server that sent the message.
If the customer opens the details of the sender, they'll see the "Email Sent As" email address in the From field and the Sendgrid server in the Mailed By field.
When your customer replies to that message, it will go back to the inbox of the person who sent it. They will see that message on their dashboard and in the contacts project.
For more information on using the 17hats mail server as your Outgoing Server, please click the button below.