As others have said, there are different ways to do it depending upon what you want the other guy to get.
The simplest thing for a mix is to bounce all the tracks in a project using the same start point. The tracks will line up from the ... start of the file. This is how to do transfers if the other party is doing the mixing from scratch.
You can freeze and bounce tracks using the same time format as above if you want to use your fx and settings.
OMF, which is supposed to transfer a lot of mix info, including which effects. This works if both parties have the same effects, naturally.
W/ ProTools, watch out for the actual tracks starting 5-10 minutes or more into the timeline.
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