How multitransport works?

[carlos]

Hi, I have a few questions about how multitransport works. Let’s say we have two users, Alice and Bob. Alice uses relay1 and relay2 while Bob uses relay3 and relay4. If Alice sends a message to Bob, which relays does she use to send it? does she use the default relay, a random one, or both? does she send the message to only one Bob relay or both?.

Also, which relays Alice uses when she writes in “Saved Messages” and has multidevice enabled?

[link2xt]

Currently there is a primary relay that is manually selected with a checkmark or radio button in the interface. Your contacts will send messages to the relay they have seen you using the last time. Same for “Saved messages”, they are sent and received using the currently selected primary relay.

I also just wrote this howto with some screenshots, you can see how to select the default relay there:

How to migrate your profile to another relay

Let’s say you have initially created a profile on the default relay and want to migrate away from it. Update at least to 2.33 on all your devices: Help testing upcoming Delta Chat 2.33.* release! Updating all your devices is required if you have multiple of them as only 2.33+ releases support using multiple relays, have an UI for it and can receive synchronization messages to update the list of relays. If you have not upgraded all your devices yet or do not have them around e.g. because you …

In the future we want to automate this, e.g. do some failover in case your primary relay is unreachable, and send to multiple relays of the contact, but in 2.33 releases most of the time only one relay is used and non-primary relay is just to receive messages from contacts that don’t know that you have changed your primary relay yet.