I'd like to send out a mail with a message by a build step. I try to find the help by TeamCity REST API but get no results.
Is there a rest api or any other way supported this?
Currently there is no support for sending emails from the build. you can use usual tools you would use from a command line.
Ok. It's a pity that TeamCity has no such support yet. I have turned to use Amazon SMS(simple mail service) to send out a customized mail notification. It's from command line, as you suggest.