Content:
1. Introduction - create your first comment
2. How to mention users in your comments?
3. How to send a comment as an email from the card?
4. How to edit or delete a card comment?
5. How to attach a file to a card comment?
6. How to expand a comment?
1. Introduction
Creating card comments is the easiest way to communicate with your team and share task-related information with the rest of the team members.
The Card Comments tab facilitates team collaboration and email management from the card.
A rich-text editor that supports markdown becomes available in the Comment text box.
Type your message and click Add Comment to the bottom right corner of the card or press the Spacebar to add your message.
Note: Alternative ways to open your Comments tab is using the Card Context menu or the Comments icon of your closed card view.
The system allows you to add as many comments as needed.
For everyday work with the cards, it is very useful to see the number of comments in the respective tab. This way, you can get a very quick idea if the task has initiated further team discussions, mentions, or remarks.
You can also use the filter at the top right corner. Just type in a keyword string to display only comments that contain your input. All others will be hidden. To remove the filter, delete the keyword.
2. How to mention users in your comments?
If you want to get your colleague’s attention (a registered Kanbanize user) on a specific topic or simply want to communicate via the card, you can use the “@” mention symbol.
Press "Space" to add a comment. Once you type in “@“ → the system opens up a drop-down list with the names of all registered users in the account. Select the user that you want to notify or approach and type your message.
If a few team members leave comments to the card -> they will be added in a chat-like format for more structured and easy-to-follow communication. 
3. How to send a comment as an email from the card?
Important: if you want to send your comment as an email, use the slider to switch to the email client mode of the card. For more information, please check the dedicated article.
4. How to edit or delete a card comment?
If you want to edit or delete a card comment, open the Comments tab, hover over the corresponding Comment, and use the respective icons. 
Note: You can only edit comments created by yourself unless you have "Account Owner" role or you are a Workspace Manager on the board where the card is located.
Comments, which are sent as emails cannot be modified at all.
5. How to attach a file to a card comment?
When you start writing a comment an Add File button will appear. When you click it, a drop-down will open up with all the locations from which you can attach a file.
6. How to expand a comment?
When a comment becomes too long, a down-facing arrow appears that will allow you to expand a comment so you can read the whole text.
There is also an option to expand all comments of a card in the top right corner.