Telegram supports direct messages to channels, which can also be used to suggest (even paid) channel posts.
While in the API direct channel message groups are sometimes called "monoforums" they actually share more similarities with the saved messages API.
channel#fe685355 flags:# creator:flags.0?true left:flags.2?true broadcast:flags.5?true verified:flags.7?true megagroup:flags.8?true restricted:flags.9?true signatures:flags.11?true min:flags.12?true scam:flags.19?true has_link:flags.20?true has_geo:flags.21?true slowmode_enabled:flags.22?true call_active:flags.23?true call_not_empty:flags.24?true fake:flags.25?true gigagroup:flags.26?true noforwards:flags.27?true join_to_send:flags.28?true join_request:flags.29?true forum:flags.30?true flags2:# stories_hidden:flags2.1?true stories_hidden_min:flags2.2?true stories_unavailable:flags2.3?true signature_profiles:flags2.12?true autotranslation:flags2.15?true broadcast_messages_allowed:flags2.16?true monoforum:flags2.17?true forum_tabs:flags2.19?true id:long access_hash:flags.13?long title:string username:flags.6?string photo:ChatPhoto date:int restriction_reason:flags.9?Vector<RestrictionReason> admin_rights:flags.14?ChatAdminRights banned_rights:flags.15?ChatBannedRights default_banned_rights:flags.18?ChatBannedRights participants_count:flags.17?int usernames:flags2.0?Vector<Username> stories_max_id:flags2.4?int color:flags2.7?PeerColor profile_color:flags2.8?PeerColor emoji_status:flags2.9?EmojiStatus level:flags2.10?int subscription_until_date:flags2.11?int bot_verification_icon:flags2.13?long send_paid_messages_stars:flags2.14?long linked_monoforum_id:flags2.18?long = Chat;
message#9815cec8 flags:# out:flags.1?true mentioned:flags.4?true media_unread:flags.5?true silent:flags.13?true post:flags.14?true from_scheduled:flags.18?true legacy:flags.19?true edit_hide:flags.21?true pinned:flags.24?true noforwards:flags.26?true invert_media:flags.27?true flags2:# offline:flags2.1?true video_processing_pending:flags2.4?true paid_suggested_post_stars:flags2.8?true paid_suggested_post_ton:flags2.9?true id:int from_id:flags.8?Peer from_boosts_applied:flags.29?int peer_id:Peer saved_peer_id:flags.28?Peer fwd_from:flags.2?MessageFwdHeader via_bot_id:flags.11?long via_business_bot_id:flags2.0?long reply_to:flags.3?MessageReplyHeader date:int message:string media:flags.9?MessageMedia reply_markup:flags.6?ReplyMarkup entities:flags.7?Vector<MessageEntity> views:flags.10?int forwards:flags.10?int replies:flags.23?MessageReplies edit_date:flags.15?int post_author:flags.16?string grouped_id:flags.17?long reactions:flags.20?MessageReactions restriction_reason:flags.22?Vector<RestrictionReason> ttl_period:flags.25?int quick_reply_shortcut_id:flags.30?int effect:flags2.2?long factcheck:flags2.3?FactCheck report_delivery_until_date:flags2.5?int paid_message_stars:flags2.6?long suggested_post:flags2.7?SuggestedPost = Message;
messageService#7a800e0a flags:# out:flags.1?true mentioned:flags.4?true media_unread:flags.5?true reactions_are_possible:flags.9?true silent:flags.13?true post:flags.14?true legacy:flags.19?true id:int from_id:flags.8?Peer peer_id:Peer saved_peer_id:flags.28?Peer reply_to:flags.3?MessageReplyHeader date:int action:MessageAction reactions:flags.20?MessageReactions ttl_period:flags.25?int = Message;
inputReplyToMonoForum#69d66c45 monoforum_peer_id:InputPeer = InputReplyTo;
inputReplyToMessage#869fbe10 flags:# reply_to_msg_id:int top_msg_id:flags.0?int reply_to_peer_id:flags.1?InputPeer quote_text:flags.2?string quote_entities:flags.3?Vector<MessageEntity> quote_offset:flags.4?int monoforum_peer_id:flags.5?InputPeer todo_item_id:flags.6?int = InputReplyTo;
monoForumDialog#64407ea7 flags:# unread_mark:flags.3?true nopaid_messages_exception:flags.4?true peer:Peer top_message:int read_inbox_max_id:int read_outbox_max_id:int unread_count:int unread_reactions_count:int draft:flags.1?DraftMessage = SavedDialog;
updateReadMonoForumInbox#77b0e372 channel_id:long saved_peer_id:Peer read_max_id:int = Update;
updateReadMonoForumOutbox#a4a79376 channel_id:long saved_peer_id:Peer read_max_id:int = Update;
updateDraftMessage#edfc111e flags:# peer:Peer top_msg_id:flags.0?int saved_peer_id:flags.1?Peer draft:DraftMessage = Update;
updateChannelReadMessagesContents#25f324f7 flags:# channel_id:long top_msg_id:flags.0?int saved_peer_id:flags.1?Peer messages:Vector<int> = Update;
updateDialogUnreadMark#b658f23e flags:# unread:flags.0?true peer:DialogPeer saved_peer_id:flags.1?Peer = Update;
updateMessageReactions#1e297bfa flags:# peer:Peer msg_id:int top_msg_id:flags.0?int saved_peer_id:flags.1?Peer reactions:MessageReactions = Update;
---functions---
channels.updatePaidMessagesPrice#4b12327b flags:# broadcast_messages_allowed:flags.0?true channel:InputChannel send_paid_messages_stars:long = Updates;
messages.getSavedDialogs#1e91fc99 flags:# exclude_pinned:flags.0?true parent_peer:flags.1?InputPeer offset_date:int offset_id:int offset_peer:InputPeer limit:int hash:long = messages.SavedDialogs;
messages.getSavedDialogsByID#6f6f9c96 flags:# parent_peer:flags.1?InputPeer ids:Vector<InputPeer> = messages.SavedDialogs;
messages.getSavedHistory#998ab009 flags:# parent_peer:flags.0?InputPeer peer:InputPeer offset_id:int offset_date:int add_offset:int limit:int max_id:int min_id:int hash:long = messages.Messages;
messages.readSavedHistory#ba4a3b5b parent_peer:InputPeer peer:InputPeer max_id:int = Bool;
messages.deleteSavedHistory#4dc5085f flags:# parent_peer:flags.0?InputPeer peer:InputPeer max_id:int min_date:flags.2?int max_date:flags.3?int = messages.AffectedHistory;
messages.search#29ee847a flags:# peer:InputPeer q:string from_id:flags.0?InputPeer saved_peer_id:flags.2?InputPeer saved_reaction:flags.3?Vector<Reaction> top_msg_id:flags.1?int filter:MessagesFilter min_date:int max_date:int offset_id:int add_offset:int limit:int max_id:int min_id:int hash:long = messages.Messages;
messages.getSearchCounters#1bbcf300 flags:# peer:InputPeer saved_peer_id:flags.2?InputPeer top_msg_id:flags.0?int filters:Vector<MessagesFilter> = Vector<messages.SearchCounter>;
messages.getSearchResultsCalendar#6aa3f6bd flags:# peer:InputPeer saved_peer_id:flags.2?InputPeer filter:MessagesFilter offset_id:int offset_date:int = messages.SearchResultsCalendar;
messages.getSearchResultsPositions#9c7f2f10 flags:# peer:InputPeer saved_peer_id:flags.2?InputPeer filter:MessagesFilter offset_id:int limit:int = messages.SearchResultsPositions;
messages.markDialogUnread#8c5006f8 flags:# unread:flags.0?true parent_peer:flags.1?InputPeer peer:InputDialogPeer = Bool;
messages.getDialogUnreadMarks#21202222 flags:# parent_peer:flags.0?InputPeer = Vector<DialogPeer>;
messages.updatePinnedMessage#d2aaf7ec flags:# silent:flags.0?true unpin:flags.1?true pm_oneside:flags.2?true peer:InputPeer id:int = Updates;
messages.unpinAllMessages#62dd747 flags:# peer:InputPeer top_msg_id:flags.0?int saved_peer_id:flags.1?InputPeer = messages.AffectedHistory;
messages.getUnreadReactions#bd7f90ac flags:# peer:InputPeer top_msg_id:flags.0?int saved_peer_id:flags.1?InputPeer offset_id:int add_offset:int limit:int max_id:int min_id:int = messages.Messages;
messages.readReactions#9ec44f93 flags:# peer:InputPeer top_msg_id:flags.0?int saved_peer_id:flags.1?InputPeer = messages.AffectedHistory;Direct channel messages can be toggled using channels.updatePaidMessagesPrice, passing the ID of the channel to channel: the same method can also be used to set a price in Telegram Stars users must pay to send direct messages to the channel (or to send messages to the supergroup, see paid messages »).
Once enabled, the channel.broadcast_messages_allowed flag will be set and the channel.linked_monoforum_id will be automatically populated with the ID of a new special supergroup, also called a monoforum.
To send a direct message to the channel, users simply have to send a message to the associated monoforum: unlike for normal supergroups/forums there's no need to join it.
Monoforums have the following special characteristics:
The channel.id of a monoforum will have a range different from those of normal supergroups and channels (this is especially relevant when generating and categorizing the associated bot API ID, see here » for the correct procedure to use for monoforum IDs).
The channel.monoforum flag will be set only for the monoforum.
The channel.broadcast_messages_allowed flag will be set only for the associated channel.
The channel.linked_monoforum_id of the monoforum will be set to the ID of the associated channel.
linked_monoforum_id of the associated channel will be set to the ID of the associated monoforum. All messages sent to the monoforum are split into "topics", reusing the same UI used for tabbed forums (note: monoforums should use the tabbed forum UI regardless of the value of channel.forum_tabs).
Each topic is associated to exactly one user, and contains only the direct message history between the user and the channel itself.
Topics are identified by the saved_peer_id field of message and messageService, which will be equal to the ID of the user.
Of course, this means monoforum topics do not share their implementation with forum topics (which is based on threads): this also means that, unlike normal forums, monoforums fully support message threads, as they are not used for topics.
Note that the message.saved_peer_id field is also used to implement a distinct feature, saved message dialogs »: in this case, the peer_id will be equal to the ID of the currently logged in user, instead of the ID of a monoforum.
Administrators of the channel with the manage_direct_messages admin right » can view and reply to all messages sent by all topics of the monoforum.
To send messages to a specific monoforum topic/user, when invoking messages.sendMessage and the other methods, channel administrators must pass an inputReplyToMonoForum to reply_to, with monoforum_peer_id equal to the topic ID (aka saved_peer_id): the resulting outgoing message will have a saved_peer_id equal to the passed monoforum_peer_id (equal and set for both for the administrator, and for the receiving user).
The message will be sent on behalf of the channel associated to the monoforum (i.e. send_as will be forcefully set by the server to the (monoforum's) channel.linked_monoforum_id): custom send_as values are not allowed and are simply ignored.
To reply to a message within a monoforum topic, pass inputReplyToMessage with the reply_to_msg_id and other flags populated as usual, and monoforum_peer_id equal to the topic ID (aka saved_peer_id); unlike for normal forums, do not populate top_msg_id.
The following methods can all be used by channel administrators to work with monoforums.
parent_peer equal to the ID of the monoforum to obtain the topic list, or a subset of the topic list, always returned as a monoForumDialog. The following methods require parent_peer to be set to the ID of the monoforum, and peer to be set to the ID of the topic (otherwise, they will affect saved/normal dialogs instead of monoforum topics):
messages.updatePinnedMessage can be used to pin a message in a topic just by passing the monoforum ID to peer and the message ID to id (the message will be automatically pinned in the containing topic, not in all topics); messages pinned in a topic can be fetched as described here », with the difference that when invoking messages.search, peer must be equal to the ID of the monoforum and saved_peer_id=id of the topic.
Use messages.unpinAllMessages to unpin all messages in a monoforum, and optionally set the saved_peer_id flag to unpin only messages within the specified topic.
To search for messages within a miniforum, use the usual messages.search, messages.getSearchCounters, messages.getSearchResultsCalendar, messages.getSearchResultsPositions methods with peer=ID of the monoforum.
To search for messages within a miniforum topic, additionally set the saved_peer_id to the id of the topic.
messages.getPinnedSavedDialogs, messages.toggleSavedDialogPin, messages.reorderPinnedSavedDialogs can only be used for saved messages, not monoforums.
Admins will receive updateReadMonoForumInbox/updateReadMonoForumOutbox updates instead of updateReadChannelInbox/updateReadChannelOutbox.
Admins will also receive an additional saved_peer_id flag in updateDraftMessage, updateChannelReadMessagesContents, updateDialogUnreadMark, updateMessageReactions updates received from monoforums, containing the topic ID.
Non-administrators can only view and send messages to their own topic.
To send a direct message to the channel, users simply have to send a message to the associated monoforum: unlike for normal supergroups/forums there's no need to join the monoforum.
Outoing and incoming monoforum messages will still be identified by the saved_peer_id, but there's no need to set inputReplyToMonoForum or inputReplyToMessage.monoforum_peer_id when sending messages to the monoforum.
From the user side monoforums are, as the name implies, monotopic forums, so they should be treated similarly to supergroups when working with the API.
For graphical clients, the user-side UI should be similar to the one used for one-to-one chats.
To interact with messages in a monoforum as a (non-admined) user, use all the methods usually used for supergroups, not the messages.*Saved* variants, without any of the modified saved_* arguments listed above, which can only be used by monoforum admins.
The same goes for some updates: non-admin users will never receive an additional saved_peer_id flag in updateDraftMessage, updateDialogUnreadMark, but they will receive it for updateMessageReactions, updateChannelReadMessagesContents.
Likewise, non-admin users will never receive updateReadMonoForumInbox/updateReadMonoForumOutbox updates instead of updateReadChannelInbox/updateReadChannelOutbox
---functions---
channels.updatePaidMessagesPrice#4b12327b flags:# broadcast_messages_allowed:flags.0?true channel:InputChannel send_paid_messages_stars:long = Updates;
The channel owner can choose to charge a certain amount of stars to users that wish to send them direct messages.
To enable or disable paid direct messages, populate the send_paid_messages_stars field of channels.updatePaidMessagesPrice accordingly: remember, always pass to channel the ID of the channel, not the ID of the linked monoforum (this is in contrast with paid messages in supergroups or normal forums, where channel must take the ID of the supergroup/monoforum).
See here » for more info on the full flow.