XNAT relies on its mail servers to send messages to its users as well as to alert admins when certain events happen. In addition, a properly configured mail server is necessary for users to be able to get sent links to reset their password when they forget it.
Mail Server Settings
This switchbox controls whether you want to enable Simple Mail Transfer Protocol (SMTP), which is how XNAT sends email. If you disable this, then emails will not be sent.
This is the address of the SMTP server that you want XNAT to use to send mail. Your institution may have a mail server you want to use, or you can find the SMTP server information for your prefered email service (such as Gmail).
This is SMTP port you want XNAT to use.
This is the username you want XNAT to use for accessing the SMTP server. For some servers, you can leave the username and password blank. If using Gmail, this will be your Gmail address.
This is the password you want XNAT to use for accessing the SMTP server. For some servers, you can leave the username and password blank. If using Gmail, you will need to get an application-specific password for XNAT so it can send email using your account.
This is the protocol you want XNAT to use, which you will want to set to 'smtp'.
This indicates whether the SMPT AUTH extension of SMTP should be used for sending email. Many mail servers require SMTP AUTH.
If true, this enables switching to a connection that is protected by Transport Layer Security (TLS) before logging in to the email server. For some servers, such as Gmail, you will want to enable this.
This is a whitespace-separated list of trusted hosts. If set to '*', all will be trusted. If this is left blank, then trust will be based on certificates.
This is what you want to show up at the beginning of the Subject for all emails sent from XNAT. This is often the name of your site, or an abbreviation of it, and makes it easier for your users to see at a glance that they have received an email from your XNAT instance.