# What Broadcast is and how sending works > Learn what Broadcast does, what your email provider does, and how Broadcast orders and paces transactional email, sequences and broadcasts. Source: https://sendbroadcast.net/university/getting-started/how-broadcast-works Before you install anything, it helps to know which jobs Broadcast does and which jobs it hands to other services. After this lesson you can explain where your email goes after you click **Send**, and why some email arrives before other email. ## Broadcast manages, your provider delivers Broadcast is the software you run on your own server. It keeps your subscribers, builds your emails, runs your automations, and records what happens to each message. It does not deliver mail to inboxes itself. For delivery, you connect an email provider, such as Amazon SES, Postmark, SendGrid or Mailgun, or any SMTP server. Broadcast hands each message to that provider, and the provider delivers it. Broadcast calls each connection an **email server**. This split matters for two reasons: 1. Your sending reputation lives with your provider account and your domain, not with Broadcast. If you change tools later, you keep it. 2. Your cost to send is your provider's price. Broadcast adds no per-email fee. The [choose an email provider](/how-to/choose-an-email-provider) guide compares the options. You connect one in lesson 5. 1. **Broadcast** On your server. Keeps the list, builds the email 2. **Email provider** Amazon SES, Postmark, SendGrid, Mailgun or SMTP 3. **Inbox** The reader's mailbox provider ↩ The provider reports deliveries, bounces and complaints back to Broadcast Broadcast builds and tracks each email. Your provider delivers it and reports what happened. ## Channels hold everything Inside Broadcast, the main unit is the **channel**. Other tools call this a list. Each channel has its own subscribers, email servers, sender details, templates, forms and reports. Nothing leaks from one channel to another. One installation can run many channels. A common setup is one channel per newsletter or per brand. You create your first channel the first time you open the dashboard. See [Channels](/docs/channels) for the details. ## Three types of email From a channel you send three types of email: 1. **Transactional emails**: one email to one person, sent through the API. A login code, a password reset or a receipt. 2. **Sequences**: automated emails sent step by step to each subscriber who enrolls. A welcome series is the classic example. 3. **Broadcasts**: one email sent to many subscribers at once. A newsletter. Broadcast also sends a few emails of its own through your email servers, such as opt-in confirmation emails and test sends. ## The priority order The three types always go out in the same order: transactional emails first, sequences second, broadcasts last. The reason is what each email costs you when it is late. A login code that arrives after ten minutes is a support ticket. A newsletter that arrives after ten minutes is fine. So when several sending jobs wait, a worker takes the one with the highest priority first. Broadcast also keeps one worker thread for transactional email only, so a login code never waits behind a long broadcast job. ## The hourly limit Every email server has an **emails per hour** limit. The default is 200 and the lowest value is 15. You set it in **Settings → Email Servers**. Set it to your provider's real quota: too low makes broadcasts slow, too high lets the provider refuse your mail. The hour is a rolling window. Broadcast counts the emails the server sent in the last 60 minutes, and it never sends above the limit. Every email counts, including tests and confirmation emails. When a server sends more than one type of email, the lower-priority types stop before the full limit. On a server that sends all three types, broadcasts stop at 80% of the limit and sequences at 90%. The rest is kept for the email that matters most. At the default of 200, a broadcast sends up to 160 emails in the hour. - Broadcasts stop here (80%): 160 - Sequences stop here (90%): 180 - Transactional email can use the full limit: 200 On a server with the default limit of 200 emails per hour that sends all three types. ## What happens to a large broadcast Say you send to 1,000 subscribers through that server. Broadcast sends the 160 that fit. Then the broadcast waits. It does not hold a worker while it waits, and it stays in the **Sending** status. As old emails leave the hourly window, it sends again, until everyone has it. You do not need to do anything. 1. **Sends 160** What fits in the hour 2. **Waits** Stays in Sending and holds no worker 3. **Room opens** Old emails leave the 60-minute window 4. **Sends again** Repeats until everyone has it A large broadcast through that server. You do not need to do anything at any step. If a server is full, its email waits for room on that server. Broadcast does not move it to another server. This is why the docs recommend two servers: one for broadcasts, and one for transactional email and sequences. Then a newsletter never uses the room your login codes need. ## Each recipient gets a broadcast once Immediately before Broadcast hands an email to the provider, it records that this recipient's send has started. Every later attempt checks that record. So a restart, a retry or a crash in the middle of a send cannot mail anyone twice. After a restart, a broadcast continues from where it stopped. The full rules, with the reserve table and the Pause and Resume behaviour, are in [How sending works](/docs/how-sending-works). ## What you learned - Broadcast manages your list and your email. Your email provider delivers it. - A channel holds its own subscribers, servers and settings. - Transactional email goes first, then sequences, then broadcasts, inside each server's hourly limit. - A large broadcast sends what fits, waits for room, and continues by itself without duplicates. ## Quiz 1. Who delivers the email when you send a broadcast? - Broadcast's own mail server, built into the install - The email provider you connect, such as Amazon SES or Postmark (correct) - Sendbroadcast.net, on your behalf Broadcast does not send mail itself. It hands each message to an email provider you control. 2. In which order does Broadcast send the three types of email? - Broadcasts, then sequences, then transactional emails - Sequences, then broadcasts, then transactional emails - All three types share one queue, first in, first out - Transactional emails, then sequences, then broadcasts (correct) Transactional email always goes first, sequences second, and broadcasts last. 3. What happens when a broadcast is larger than the room left in the server's hourly limit? - It sends what fits, waits for room, and continues by itself (correct) - It fails and you must resend it - It moves the rest to another email server in the channel The broadcast stays in Sending, waits for room on the same server, and continues by itself.