What is a “probation period” for new senders?

You've just set up a shiny new sending domain or IP, authenticated everything correctly, and you're ready to go. But mailbox providers don't know you yet. You're a stranger, and strangers don't get the same treatment as trusted regulars. That's the probation period in a nutshell.

When a new IP or domain starts sending, providers like Gmail, Outlook, and Yahoo Mail have nothing to go on. No history, no reputation score, no pattern of behavior. So they throttle your volume and scrutinize your content more aggressively than they would for an established sender. That's not a bug. It's how they protect their users from new bad actors.

How long does probation last? Typically 4 to 8 weeks for a well-managed warm-up. Gmail tends to evaluate reputation signals within the first 30 days quite heavily. Yahoo and Outlook can take a bit longer to fully trust a new source. If you're sending badly during those weeks, probation doesn't just extend. It can leave a permanent mark on your reputation that's hard to recover from.

What volume can you actually send? There's no universal published number, but a sensible starting point looks something like this:

• Week 1: 200 to 500 emails per day, to your most engaged contacts
• Week 2: 1,000 to 2,000 per day
• Week 3: 5,000 per day
• Week 4 onward: double roughly every 5 to 7 days, as long as your metrics stay healthy

These aren't hard limits set by any provider. They're a pacing guide based on what most providers can observe and model without flagging you as suspicious. Slow and steady wins here (of course, easier said than done when you've got a list of 50,000 waiting).

What helps you graduate faster? Authentication is the foundation. If your SPF, DKIM, and DMARC records aren't in place before you start warming, you're making probation harder for yourself. Beyond that, the signals that actually move the needle are engagement signals. Opens, clicks, replies, and moving emails out of spam all tell providers that real humans want your mail. Low complaint rates and near-zero hard bounces confirm that your list is clean and you know what you're doing.

A few things that will extend your probation or kill it entirely: sending to old, unvalidated lists, high bounce rates above 2%, spam complaints above 0.1%, and volume spikes that don't follow a gradual curve. Providers notice all of this.

How do you know when probation is over? You won't get a certificate. The signs are practical: your emails start landing in the inbox consistently, deferrals drop off, and you can scale volume without seeing sudden increases in spam folder placement. Tools like Google Postmaster Tools will show your domain reputation moving from "low" toward "medium" and eventually "high". That's your graduation signal.

Still if you're about to start warming a new IP or domain, make sure your list is clean before you begin. Sending to bad addresses during probation is one of the fastest ways to stall before you even get started. If you want a second pair of eyes on your setup before you flip the switch, our SOS hotline is free and there's no pitch waiting on the other end.