Here’s what’s up with that
You might reasonably suggest, “Hey, if that’s the case, just add more servers!” But every network has limits. We could add a thousand email servers, but there would still be a theoretical choke point at the network level. If it was simply a question of adding more servers, email giants like Google and Yahoo wouldn’t have sending limits. But they do, for more or less the same reasons we do.
Spam
Then there is spam. We have very stringent fraudulent account prevention measures in place. But occasionally a bad apple does slink through. Typically within minutes of the account being set up, email starts to flow. Spam email. Our rate limiters kick in and say, “Hold on there, sport, you can’t do that,” and we avoid allowing a large amount of spam to escape.
We have a pretty speedy team here that takes care of blacklisting, but there is still a negative impact on email service for those servers while we get them de-listed. And as any farmer can tell you, it’s better to close the barn door before the cows get out and run wild. If cows can run wild. I think they can, according to old cowboy movies.
A sterling reputation
Finally, there is something called server reputation. This is an important thing. When you set up a new email server with a new IP address, the big recipients (Google, Yahoo, AOL, large ISPs) all see messages coming from a new IP and say, “I’ve never seen that server before, let’s make sure this is legit,” so they pay very close attention to the messages.
Every large recipient has their own way to calculate server reputation, but the gist of it is the same everywhere. They “grade” the server according to spam complaints registered by their own users. That negative feedback can affect the server’s reputation, especially when a server is relatively “young.” The more “clean” messages that go out, the better the server’s reputation.
The better the server’s reputation, the less likely that legitimate messages will wind up in a recipient’s junk, trash or spam folder. But even a server with a very good reputation can be penalized by one large spam incident, so you can see why it’s important to protect that reputation.
So in a nutshell
Our primary goal is a seamless and trouble free service for every one of our users. Sometimes providing that experience comes at the expense of allowing certain things. Mass emailing is one of those things. So if you have a need to send out a large amount of mail on a regular basis, we recommend using a third-party mailing service. There are a lot of them out there, from commercial web-interface services like Constant Contact, to API-based services geared more toward developers, like Mailgun and SendGrid.