In Geograph, they have a method whereby you can click to link to another member and add an off-site message, and they in turn can reply. This avoids, though not completely, the problem with 'thread drift', or 'Fred Drift' as it is called there. The thread 'Introduce yourself here' soon drifted off at a tangent, which is hard to avoid, but some threads can quickly loose the plot if not checked. A hint from the Mods to start a new thread usually ends the 'drift'.
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