Related Clues:

• Button often indicated by a forward arrow
• Button to transmit a text
• Come back to accept a solution for unresolved contest
• Deal with an email error message, maybe
• Email out
• Dispatch, transmit
• Word before "packing" or "flying"
• Fabric-covered walls of library echo
• Fire off, as an email
• "__ my regards"
• Button that may submit an online form
• Place in the outgoing mail
• Chat box button
• Ctrl+Enter, in an email app
• Button often clicked too soon