How to avoid sending the email of a new user?
In our installation we don't need to send the email with the password because we have implemented the single sign-on to connect to Appian.
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In the past i've done this by utilizing the "Create User with i18n" smart service contained in the Personalization Utilities plug-in; it's intentionally set up to not send an email out when the account is created (it also allows you to procedurally generate a strong "junk" password to assign to the user as their permanent password upon creation, which must be done even though SSO users will never actually use their password).
Edit: and, the option Carlos mentioned before I managed to submit the reply I was still typing, which might be better if you don't want to use a plug-in. I'm not sure I actually knew about that one yet.