Pharmanode - When you select Pharmanode, Your sender email domain will be replaced with @pharmanode.es and your domain name will be added to your name. I.e. if the sender email is firstname.lastname@example.org, it will be replaced with email@example.com. This way of sending is more secure and avoid that the mail goes into the recievers spam mailbox. If someone reply to this email, you will recieve it to the email you originally wrote
Default - If you are using Default, the sending email will be exactly as you have written it. This is a bit more insecure and there is a risk that the mail end up in the recievers spam.