I would like to know how I can send emails from my web app that I have hosted in a shared server. First of all I would like to know if I can, so my question is: what should I check?
I heard that I should have a mail server in my hosting, so I tried telnet smtp.tirengarfio.com 465, but I get:
telnet: could not resolve smtp.tirengarfio.com/465: Name or service not known
tirengarfio.com is the domain where the webapp is hosted.
What can I do?
You need to review the hosting specifications or to consult the hosting support whether a SMTP server is included in the hosting package.
If any is provided, you'll get to know the needed hostname and port. If none is provided, you'll need to grab another one or to install a custom one. You can make use of the mail server of your ISP or public mailboxes like Yahoo/Gmail/etc, but you're only restricted to sending mails from your own account (thus your account appears in the from header). The hostname/port is specified in the documentation/FAQ of the ISP/mailprovider in question. The username/password is of course the same as your own account name/password over there.
If you rather want to have full control over the mail server, you'll need to install your own mail server, for example Apache James. This only works if you have a dedicated hosting/server.