I got a mail and replied to it.
After that I got a new mail, but I can't find it anywhere to continue the conversation.

Is it a bug or do I have to look somewhere specific.

Did you check your inbox?

If it vanished from your inbox, the only thing that might have done that is an accidental delete.

If mail vanishes from your inbox, chances are something happened to the account of the sender. That tends to happen sometimes, check your outbox.

And if mail's gone from your outbox, chances are it got deleted from the other guy's inbox.

The mail system on this site is bizarre sometimes. My understanding is that you can’t delete your own outgoing messages, but you can delete incoming messages from other people (and if you do, it deletes it from the other person’s outbox?)

There’s been a few instances in which people messaging me claimed to have not seen a certain message that I’ve sent, and it makes me wonder how many times I’ve accidentally ghosted someone, or they’ve ghosted me because the pming system on this site is broken.