While our app provides users with a way to send messages to Junk/Spam folders, any future messages you receive from this sender may not be filtered automatically. Automatic junk handling/classification of your messages is something that's handled server-side by your email provider, and unfortunately third-party email apps (including ours) have control over this. Additionally, third-party email apps aren't permitted to train your spam account's spam filter.
If you continue to receive unwanted messages, we'd recommend logging into your email account outside of Edison Mail, via your provider's webmail. Once there, mark the message as "spam" or "not spam" and the filter should be properly trained.