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i'm implementing a webmail app as we speak (from the bottom up). my immediate thought was "wtf are 'conversations', gmail? of course i want threads!". then i s

i'm implementing a webmail app as we speak (from the bottom up). my immediate thought was "wtf are 'conversations', gmail? of course i want threads!". then i started actually handling the raw email messages. i got threads working pretty well but noticed frequent rendering issues and digging into the cause. my conclusion is, email threading is mostly a pipe dream; it can only be done properly if you have a view of the entire conversation (as is the case with centralized forums/message stores like HN). the 'References:' header only represents the message ids of any particular branch up to the root. if you try turning a number of messages with the same root into proper threads, you quickly discover missing branches, partial branches/holes, missing leaf nodes, etc. If your knowledge of a thread starts with a message forwarded to you, no thread is possible (even though one clearly exists as indicated by the References chain in the header!). side-conversations that happen (selective replies, cc/bcc), additional fwd/reply chains are all invisible to you. sadly, an incomplete thread view is an extremely common thing (at least in my inbox/sent of ~15k messages). the client can only thread the actual raw messages it has; those simply quoted in any replies or forwards (which established the Reference chains) don't count. the only commonality you have is knowing the root message id and the timestamp for ORDER BY. everything in between, you may or may not have to reconstruct a partial view of the thread...and each user will have a different view of that thread based on which parts they've been party to. the threading that i did get working was nice, but not as useful as a bulletproof solution would have been. unfortunately, i don't believe that's possible with email. i now understand why gmail does flat convos.

ori_b 9y ago
> my conclusion is, email threading is mostly a pipe dream Them why has it been working so well for me since I started using email? Maybe take a look at this for inspiration: https://fkref.com/?RbC_-NEE https://fkref.com/?RbC_-NEE
- leeoniya 9y ago
  thats basically what i did. the problem is with this step: 4. Prune empty containers. you can prune/flatten these containers but then the deeper messages that you do have are not direct replies to their ancestors in the flattened/pruned version of the tree. i didnt say that threading did not work. it does. but it is imperfect at best and can be misleading at worst. in my case i was constructing an MPTT structure (Nested Set) for optimal thread fetching and simply leaving in the dummy message placeholders that i didnt have a copy of. i plan to experiment further, but there arent really any earth-shaking revelations in that post. it's all fairly obvious.

ori_b 9y ago

> my conclusion is, email threading is mostly a pipe dream Them why has it been working so well for me since I started using email? Maybe take a look at this for inspiration: https://fkref.com/?RbC_-NEE https://fkref.com/?RbC_-NEE

leeoniya 9y ago
thats basically what i did. the problem is with this step: 4. Prune empty containers. you can prune/flatten these containers but then the deeper messages that you do have are not direct replies to their ancestors in the flattened/pruned version of the tree. i didnt say that threading did not work. it does. but it is imperfect at best and can be misleading at worst. in my case i was constructing an MPTT structure (Nested Set) for optimal thread fetching and simply leaving in the dummy message placeholders that i didnt have a copy of. i plan to experiment further, but there arent really any earth-shaking revelations in that post. it's all fairly obvious.