If you have followed our MAGY series so far, you already know the landscape has changed: 

• Part 1 showed how Microsoft, Apple, Gmail & Yahoo now control inbox standards 

• Part 2 explained how to adapt with authentication, segmentation & gradual scaling 

Now let’s zoom in on the most common reasons good, permission-based email still lands in spam: mailing volumes, content and… Speed 

You can have 100% valid subscribers, great subject lines, perfect SPF/DKIM/DMARC and still get blocked because inbox providers think you are sending too fast. 

This will be the silent deliverability disruptor of 2026. 

Why sending too fast looks like spam 

Mailbox providers don’t just look at what you send, they watch how you send. 

A sudden burst of 100,000 emails is no different to them than a bot launching a spam wave. 

Algorithms now ask things like: 

• How many emails are going out per minute? 

• Does this sender ramp up gradually or all at once? 

• Did they go from dormant to high volume overnight? 

• Is the sending pattern smooth? Or spiky like an attack? 

If the answer looks risky, the mailbox reacts instantly. Gmail defers deliverability, Microsoft throws 421 soft blocks, Yahoo rate-limits your IP and Apple silently shifts your email to junk. No warnings. No diagnostics. And recovery takes weeks. 

Warm-up used to be simple — now it’s strategic 

Old warm-up advice used to be something like: Increase sending a little every day for 1–2 weeks, via a straight, directly-proportional progress line. 

That era is gone. 

Today, warm-up isn’t about how many per day, it’s about how many per minute, and how predictable you look while scaling. 

In the old deliverability era, the main concern was how many emails you sent per day. Today, the limiting factor is much more granular, inbox providers look at your per-minute sending velocity, not just total volume. 

Warm-up periods also used to be relatively short, often just a week or two. Now they are significantly longer and more strategic, often extending over multiple weeks or even months to gradually build trust. 

Where senders once relied on large batch sends, modern deliverability favours slow, steady, rhythmic trickle sending, where messages flow out gradually instead of all at once. 

And instead of scaling as soon as a list looks clean, you now scale only when engagement justifies it, meaning opens, clicks and low complaint rates act as the green light for increasing volume. In other words, growth must be earned, not assumed. 

Good sender behavior is now defined by pacing, not power. 

Slow senders look safe. Fast senders look viral, in the bad way. 

Where mySMTP MailWizz changes everything 

Here is the big deliverability advantage we built intentionally: 

Instead of sending thousands of emails at once, mySMTP MailWizz sends minute by minute, automatically. 

This approach removes the common problems that trigger filtering and throttling. There are no sudden sending bursts, no sharp rate-limit spikes, and nothing that resembles the rapid-fire behaviour of automated spam bots. Instead, delivery stays smooth and consistent, which prevents accidental velocity-based flags from being raised at mailbox providers. 

Even better, this creates a healthy warm-up pattern naturally. 

Below is a example schedule showing how speed scales safely: