SMTP vs FTP settings
SMTP settings are usually different from the login details for your FTP account. We hope the following guide would help:

FTP vs SMTP:
A FTP account is used to publish files to your website.

SMTP settings are needed when you need to send emails. For example, when a new mail account needs to be set up on the Mail app, you will be asked for your SMTP settings.

Port numbers:
The most common port number for FTP is port 21. The most common port number for a standard SMTP server is port 25. (Both port numbers are industry-standard, but web hosts have full control of port number selections and may choose to use a different port)