You can send a message to a pal at any time, however if they are 'away' or in 'do not disturb' mode they may not see your messages right away.

see online status

If a person is offline you can still send them a message. They will receive the message the next time they log in to Paltalk.

note: you may only send offline messages to Paltalk pals

see instant message a pal

see login to other IM service
see add a pal from another IM service