You can reply to a Conversation by clicking Reply or Add Message. Selecting Reply copies the previous message, like in an email, but limits your reply to the same channel the conversation is in. The Add Message option allows you to add a response in different channels.
Important Note
You cannot reply or add messages to a closed conversation.
Instructions
Navigate to the Conversations tab
Click Go to Conversation Details for the desired conversation
Click Reply or Add Message
Reply: Copy the previous message and respond in the same channel
Add Message: Respond to the conversation using any channel
Type your response
Click the Add Attachment link to add any desired attachments
Note:
The file size limit for an attachment is 20 MB.
Click Send or Log:
Send: Send your Reply
Log: Send your Message