There are two types of message templates:
- Message
- Invitation
The Message type has no limit on the number of characters unlike the Invitation type which is limited by LinkedIn to 200 for members and 300 for Premium members.
NB: for certain non-premium members, with an old account, Linkedin sometimes allows a limit of 300 characters. Having not identified a way to know what limit will be applied, in Kanbox, a free Linkedin account will have a limit of 200 characters.