Jami swarm is an asynchronous messenger?

Asynchronous. Messages sent to recipients who are offline will be delivered when the recipient reconnects, even if the sender has since disconnected.

Reading the link about swarms, I have not understood, is
jami swarm an asynchronous messenger? If it is,
if there are no servers then where are sent text messages kept
while sender and recipient are not online?

All devices in the conv is able to sync messages,

So in a group, if Alice, Bob, Carla are in a conv ; Alice sends a message when Carla is offline, Bob gets it ; then Alice goes offline ; If carla goes online, she will get the message via Bob.

I would have preferred a yes or no answer. I read your
answer as a no. My understanding about retroshare and
maidsafe is, that data, text messages are data, is moved to
a number of random online computers, running retroshare
or maidsafe software. Then when the recipient gets online, he will get the data
from those computers. This system will work, if not all
data host computers are turned off at the same time. What your
answer suggest is, that only those computers in the messenger group
are the swarm? So if there are only sender and recipient, then
the recipient will not get his data if sender and recipient
are not online at the same time. The sender’s computer will
keep on trying sending the data to the recipient?