“Unlimited Sending” refers to a software licensing model where the platform does not cap your volume, but it does not override the physical “Throttling Limits” imposed by email service providers (ESPs) like Google, Outlook, or Amazon SES. While an “Unlimited” tool allows you to push the pedal to the floor, Throttling is the speed limit of the road you are driving on. Understanding this distinction is critical for scaling past 10,000 emails a day without crashing.
The “All-You-Can-Eat” Misconception
When you buy an “Unlimited” plan from Email 360 Pro, you are buying an uncapped engine. We will never stop you from sending 1 million emails.
However, if you try to push 1 million emails through a single Gmail account in one hour, Google will stop you.
This isn’t a software limit; it’s a Server Limit. To scale effectively, you must understand the three layers of limits: The Software (Us), The Provider (Google/Outlook), and The Protocol (SMTP).
1. The Physics of Email: Burst Rate vs. Daily Rate
Limits are not just about “how many per day.” They are about speed.
The Daily Rate (The Marathon)
This is the total volume allowed in 24 hours.
- Google Workspace: ~2,000/day (Transactional) / ~50-100/day (Safe Cold Email).
- Amazon SES: Starts at 50,000/day, scales to millions.
The Burst Rate (The Sprint)
This is how many emails you can send per second.
- Scenario: You have a 20,000 daily limit on Amazon SES. You try to send all 20,000 in 1 minute.
- Result: Throttled. Amazon calculates your “Max Send Rate” (e.g., 14 emails/second). If you exceed it, the extra emails are queued or bounced with a “454 Throttling” error.
Key Takeaway: “Unlimited” software manages this for you by automatically slowing down (throttling) your campaign to match your provider’s safe burst rate.
2. Provider Limits: Know Your Road
Different roads have different speed limits.
Google & Outlook (The City Streets)
- Design: Built for human-to-human communication.
- Limit Behavior: Strict and opaque. If you send too fast, they trigger a “Temporary Lockout” (User suspended for 24 hours).
- Strategy: Low and slow. Use “Throttling” settings to send 1 email every 3-5 minutes per account.
Amazon SES / SendGrid (The Highway)
- Design: Built for application volume.
- Limit Behavior: Explicit. They tell you exactly: “You can send 50 emails/second.”
- Strategy: High speed. You can blast thousands in minutes, provided your bounce rate stays low.
3. The “Leaky Bucket” Algorithm
Most SMTP servers use a “Leaky Bucket” algorithm for throttling.
- Imagine a bucket with a small hole in the bottom (the sending rate).
- You can pour water in (sending emails) faster than it leaks out, but only until the bucket fills up.
- Once full, any extra water spills over (Throttling Errors).
Why this matters: You might be able to send 100 emails instantly (filling the bucket), but then you must wait for the bucket to drain before sending more. This is why your campaigns might start fast and then seemingly “pause.” It’s not a bug; it’s physics.
4. How “Unlimited” Software Protects You
If “Unlimited” software just blasted everything at once, you would be banned instantly. Smart software acts as a Traffic Controller.
- Queue Management: You click “Send” on 50,000 emails. The software holds them in a database.
- Drip Feeding: It releases them to the SMTP server one by one, respecting the delay you set (e.g., 60 seconds).
- Backoff Logic: If the server says “454 Throttling,” the software pauses that specific inbox for 15 minutes and retries later automatically.
5. When “Unlimited” Meets “Reputation”
There is a fourth limit: Your Reputation Cap. Even if Amazon SES says you can send 1 million emails, if your domain is 3 days old, you essentially have a limit of 0.
- The “Warm-Up” Throttle: New domains are algorithmically throttled by receivers. If you send 100 emails from a new domain, Google might deliver 10 to the Inbox and 90 to Spam, effectively “throttling” your visibility.
- The Fix: Time. You cannot hack reputation. “Unlimited” sending is the destination, not the starting line.
Frequently Asked Questions (FAQ)
Q1: If I have an Unlimited plan, why do I still need multiple inboxes? A: Because of the Provider Limits (Google/Outlook). The software is unlimited, but each Google account is limited to ~50 safe emails/day. To send 5,000/day, you need 100 accounts (50 * 100 = 5,000). The software aggregates them to create “Unlimited” capacity.
Q2: What is a “454 Throttling failure: Daily message quota exceeded” error? A: This comes from your provider (e.g., Amazon SES), not us. It means you hit your 24-hour limit. You must wait for the quota to reset (usually midnight UTC) or request a limit increase from Amazon.
Q3: Can I bypass throttling by using multiple SMTP providers? A: Yes! This is a pro move. You can connect 5 different SMTP relays (SendGrid, Mailgun, SES) to one campaign. If one throttles you, the software routes traffic to the others. This creates a “Redundant” unlimited system.
Q4: Does sending slower improve deliverability? A: Yes. Rapid spikes look like bot behavior. A steady “heartbeat” of emails (e.g., 1 every 2 minutes) looks more natural and passes spam filters more easily.
Q5: What is the maximum number of emails I can send per day with Email 360 Pro? A: Technically, there is no limit. We have clients sending 500k+ per day. The only limit is the infrastructure you connect to it.
Q6: Why does my campaign status say “Sending” but no emails are going out? A: You are likely in a “Backoff” period. If your SMTP server returned a throttling error, our system pauses for safety. Check your “Error Logs” to see if your provider is rejecting the connection.
Q7: How do I increase my Amazon SES sending limits? A: You must submit a request in the AWS console. They usually start you at 50k/day. To get to 100k+, you need to show a history of low bounce rates (<1%) and low complaint rates (<0.1%) for at least 2 weeks.
Q8: Is “Unlimited” sending legal? A: Yes, volume is not illegal. Sending unsolicited email without opt-out options (Spam) is illegal. You can send 1 million legal emails, or 1 illegal email. The number doesn’t determine legality; the content and consent do.
Q9: What is “Ramp-Up” vs. “Warm-Up”? A:
- Warm-Up: Building reputation (Trust).
- Ramp-Up: Increasing volume limits (Capacity).
- You typically do both simultaneously.
Q10: Can I set different throttling rules for different inboxes? A: Yes. You might want your “CEO” inbox to send only 20/day (high safety) while your “Sales” generic inboxes send 50/day.
Q11: What is the ideal “Time Gap” between emails? A: For Google/Outlook accounts: 3 to 7 minutes. For SMTP relays (SES): 0.1 to 1 second.
Q12: If I get throttled, do I lose those emails? A: No. A good sending platform “Retries” soft bounces. They sit in the queue and wait for the door to open again. They only fail permanently if the server rejects them with a 500 (Hard Bounce) error.
Q13: Why is my “Burst Rate” lower than my “Daily Limit”? A: Providers want to prevent spikes. They might give you 10,000/day but only allow 5/second to prevent you from overwhelming their receiving servers.
Q14: Does using a “Dedicated IP” help with throttling? A: Yes. On shared IPs, you might be throttled because other users are clogging the pipe. With a Dedicated IP, you own the entire pipe capacity.
Q15: What is the “Grey Listing” delay? A: Some receiving servers reject the first attempt from a new sender just to see if you are a real server that will retry. This causes a 15-minute delay. It looks like throttling, but it’s actually a verification test.
Master the Speed Limit
Don’t let throttling stop your growth. Configure your sending limits smartly.
[Link: Configure Throttling Settings in Email 360 Pro]