I just used the plugin image upload, but the image can't show how to fix it?
I use the v1.12.2 version, want to use the smtp service, need to install the relevant plugin, how should I set it?
That would depend on the SMTP server you are using and its configuration.
In 1.12.2 you do not need a plugin for SMTP emailer services. You can use the built-in emailer configuration.