It is possible in telegram chats to search for messages, and to filter those search results by a specific user.

However, if a user is posting as a channel, it is impossible to use that search filter, as channels are excluded from the list of possible targets when filtering by user.

I would like to request that search-by-member be expanded to support searching by channel entities, and in this case it should present messages posted as that specific channel (excluding the user's main account and any other channels they might post as).

It is important to have this feature from a chat administrative perspective, as without it, it can be difficult to find messages posted as a channel in anything but the recent past. It is also a nuisance to ordinary users who interact with masquerading channels and wish to review their conversation history.

Additional thoughts:

• If a user spams with a channel and then sets it to private, it shouldn't make the spam harder to find and eliminate
• If the group's settings are changed to disallow posting as channels but there are already such messages in the chat history, should users still be able to search with that filter? should admins be able to?