An accepted buddy relationship is more than a social link. In Inter-War it is one of the relationships that can authorize defensive fleet support on an allowed target.
How does it work?
For defensive support, the system can allow your own target, a member of the same alliance or an accepted buddy. A pending buddy request should not be treated the same as an already accepted relationship.
What are the requirements?
The support fleet still has to satisfy the mission rules, reach the correct target type and actually remain there when combat starts. A fleet that is already returning does not participate in defense.
What happens after the action?
A buddy is therefore useful when you want defensive cooperation with a player outside your alliance. It does not grant permission to join an offensive ACS Attack, which under the current rule requires the alliance relationship.
When is it useful?
Communication belongs to the local player in the current universe. This matters in multiuniverse: a message, relationship or status from one world should not automatically be treated as gameplay state in another.
Common mistakes
Use recipients visible in the current universe. If the interface pre-fills a recipient, still verify the field before sending—especially after navigating from a profile, Galaxy view or modal.
Related FAQ: How do private messages and unread counts work? · How do alliance ranks and permissions work?