Related Clues:

• Social media entry
• Letters; stake
• Sentry’s station
• Mile marker
• Grape-Nuts maker
• Picket finishes on 15 across
• Contribute to an internet forum
• Put up online
• Be an active blogger
• Opening mail
• Stop weirdo letters
• Stake for a sign
• Stick up letters in position
• Part of an Instagram feed
• Reddit entry