invisibleman18:

 

Using messenger on Android - obviously lists your conversations in order of last message (with new at the top). But also horizontally along the top it shows other contacts which are usually people you contact frequently but over the last couple of days I've had a lot of people I don't recognise appearing. I go into the conversation and it's someone I once sold something to on marketplace 8 years ago, or even someone who just messaged and never went through with the purchase etc.

 

I'm on iOS, but the same happens for me - my ex is almost always one of the people along the top horizontal areas, despite us not having messaged each other for 4+ years. 

Made it a bit awkward when my current partner first saw her there!