Do Not Subscribe Meaning

[Stephaine Zitzow]

Thefolders you subscribe to are the ones displayed by Thunderbird. It subscribes every folder it finds when you first setup the account and any folder you add through Thunderbird is automatically subscribed as well. I guess that option is there so if you were to add a folder through another application or a webmail-ish app and you wanted that new folder to be displayed as well you can just turn it on.

Generally, this will be all of the folders in your account, and only the folders in your account. However, in some situations you may find that there are folders in your account that do not appear in Thunderbird, or folders that appear in Thunderbird that are not in your account. This can be fixed by subscribing to (or unsubscribing from) the offending folders.

This is due of the peculiarities of the IMAP protocol. Strangely enough, the authors of that protocol not only thought about email when they dreamed it up, they also thought about usenet and newsgroups. The newsgroups of the usenet form a large hierarchy with thousands and thousands of groups. The original aim of IMAP was to support having the complete hierarchy available through your IMAP account. Of course, you wouldn't want all those groups to show up in your mail client, thus the concept of folder subscriptions was added to the protocol.

If I remember correctly, Thunderbird also has an option to simply show you all your available folders without going through the motions of subscribing to single folders. It has nothing to do with offline use or synchronization.

If you want to know more about the IMAP protocol, check out the corresponding Wikipedia article. You can also try to read the corresponding RFC which makes up the protocol and which is full of examples concerning usenet newsgroups (and has only a few examples that relate directly to email).

In IMAP, subscriptions are used as a way of marking which folders should be displayed by IMAP clients. Some system folders may provide functionality but not contain emails that are of interest to the user, e.g., an Exchange server contains folders such as Contacts, Journal, Sync Issues).

From a particular account: File Subscribe results in a list of folders, then: Gmailthen from a list of folders: check or uncheck the folders desired or not desired.In my case, it was eliminating Important and All.

The Marginalian has a free Sunday digest of the week's most mind-broadening and heart-lifting reflections spanning art, science, poetry, philosophy, and other tendrils of our search for truth, beauty, meaning, and creative vitality. Here's an example. Like? Claim yours:

When the wonder of birds entered my world, I came awake to the notation of starlings on the street wires, to the house wrens bathing in the dusty parking lot, to the robin serenading dawn in its clear and lovely voice, each trill as perfect as a Bach measure. One rainy afternoon, I watched two night herons sleep and wondered whether they were dreaming, went down a rabbit hole of research, wrote a The New York Times piece about how the evolution of REM in the avian brain shaped our human dreams.

Birds I already knew and loved called out to me first: the bowerbird, the nightingale, the osprey. Then I began discovering strange and wondrous creatures I had never seen: the fierce frigate, the tender linnet, the Dr. Seussian snake-bird.

The daily divinations became an unexpected consolation, helped compost the suffering into fertile ground for growth, held up mirrors I needed to look at. (Anything you polish with attention will become a mirror.)

Prompted by an innate desire to acquire a thorough knowledge of the birds of this happy country, I formed the resolution, immediately on my landing, to spend, if not all my time in that study, at least all that portion generally called leisure, and to draw each individual of its natural size and coloring.

Many people think [they are in the mode of eternity] when, having done the one or the other, they combine or mediate these opposites. But this is a misunderstanding, for the true eternity lies not behind either/or but ahead of it.

A century before Anne Morrow Lindbergh wrote so beautifully about embracing the mutability of intimate relationships, Kierkegaard considers what it takes to let a relationship change organically in order to feed the soul in a new way:

SUBSCRIBE, UNSUBSCRIBE and PUBLISH implement the Publish/Subscribe messaging paradigm where (citing Wikipedia) senders (publishers) are not programmed to send their messages to specific receivers (subscribers).Rather, published messages are characterized into channels, without knowledge of what (if any) subscribers there may be.Subscribers express interest in one or more channels and only receive messages that are of interest, without knowledge of what (if any) publishers there are.This decoupling of publishers and subscribers allows for greater scalability and a more dynamic network topology.

A client subscribed to one or more channels shouldn't issue commands, although it can SUBSCRIBE and UNSUBSCRIBE to and from other channels.The replies to subscription and unsubscribing operations are sent in the form of messages so that the client can just read a coherent stream of messages where the first element indicates the type of message.The commands that are allowed in the context of a subscribed RESP2 client are:

Please note that when using redis-cli, in subscribed mode commands such as UNSUBSCRIBE and PUNSUBSCRIBE cannot be used because redis-cli will not accept any commands and can only quit the mode with Ctrl-C.

Redis' Pub/Sub exhibits at-most-once message delivery semantics.As the name suggests, it means that a message will be delivered once if at all.Once the message is sent by the Redis server, there's no chance of it being sent again.If the subscriber is unable to handle the message (for example, due to an error or a network disconnect) the message is forever lost.

If your application requires stronger delivery guarantees, you may want to learn about Redis Streams.Messages in streams are persisted, and support both at-most-once as well as at-least-once delivery semantics.

unsubscribe: means that we successfully unsubscribed from the channel given as second element in the reply.The third argument represents the number of channels we are currently subscribed to.When the last argument is zero, we are no longer subscribed to any channel, and the client can issue any kind of Redis command as we are outside the Pub/Sub state.

message: it is a message received as a result of a PUBLISH command issued by another client.The second element is the name of the originating channel, and the third argument is the actual message payload.

Similarly to SUBSCRIBE and UNSUBSCRIBE, PSUBSCRIBE and PUNSUBSCRIBE commands are acknowledged by the system sending a message of type psubscribe and punsubscribe using the same format as the subscribe and unsubscribe message format.

A client may receive a single message multiple times if it's subscribed to multiple patterns matching a published message, or if it is subscribed to both patterns and channels matching the message.This is shown by the following example:

In subscribe, unsubscribe, psubscribe and punsubscribe message types, the last argument is the count of subscriptions still active.This number is the total number of channels and patterns the client is still subscribed to.So the client will exit the Pub/Sub state only when this count drops to zero as a result of unsubscribing from all the channels and patterns.

From Redis 7.0, sharded Pub/Sub is introduced in which shard channels are assigned to slots by the same algorithm used to assign keys to slots.A shard message must be sent to a node that owns the slot the shard channel is hashed to.The cluster makes sure the published shard messages are forwarded to all nodes in the shard, so clients can subscribe to a shard channel by connecting to either the master responsible for the slot, or to any of its replicas.SSUBSCRIBE, SUNSUBSCRIBE and SPUBLISH are used to implement sharded Pub/Sub.

Sharded Pub/Sub helps to scale the usage of Pub/Sub in cluster mode.It restricts the propagation of messages to be within the shard of a cluster.Hence, the amount of data passing through the cluster bus is limited in comparison to global Pub/Sub where each message propagates to each node in the cluster.This allows users to horizontally scale the Pub/Sub usage by adding more shards.

Because all the messages received contain the original subscription causing the message delivery (the channel in the case of message type, and the original pattern in the case of pmessage type) client libraries may bind the original subscription to callbacks (that can be anonymous functions, blocks, function pointers), using a hash table.

You can subscribe to channels you like to see more content from those channels. You can find a Subscribe button under any YouTube video or on a channel's page. Once you subscribe to a channel, any new videos it publishes will show up in your Subscriptions feed.

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