imap-smtp: Support SMTP servers that don't require authentication
imap-smtp: Support SMTP servers that don't require authentication

There is a lot of email infrastructure where SMTP is only allowed
inside a firewall and no authentication is required. We should support
such cases.

ritzk/gnome-online-accounts,Distrotech/gnome-online-accounts,halfline/gnome-online-accounts,Distrotech/gnome-online-accounts,felipeborges/gnome-online-accounts,halfline/gnome-online-accounts,Distrotech/gnome-online-accounts,dnohales/gnome-online-accounts,halfline/gnome-online-accounts,dnohales/gnome-online-accounts,ritzk/gnome-online-accounts,felipeborges/gnome-online-accounts,dnohales/gnome-online-accounts,ritzk/gnome-online-accounts,felipeborges/gnome-online-accounts