Every Mandrill account has an hourly send quota based on account reputation and typical sending volume. There are a few common reasons that you may have a low hourly quota. If you're looking for more general information about the reputation system and hourly quota, click here.
All new accounts have an "Unknown" reputation since we haven't seen the results of anything you've sent. This means new accounts start with a preset (lower) hourly quota while Mandrill gets to know the type of email you're sending, and how much. This quota will automatically adjust once you start sending emails (including tests). It's necessary to have this warm-up period where you have low limits to protect Mandrill (and you) from users who might send spam or other email that would damage our reputation.
If you're worried that your limit is too low, try sending more email. If your recipients respond positively to the messages you're sending, your quota will grow quickly. Generally, fewer bounces and fewer abuse complaints lead to better reputation. If you have a good reputation, you shouldn't be limited by your sending quota.
Mandrill uses a variety of heuristics to set each account's reputation, and as more email is sent for your account and through Mandrill, more information is available for Mandrill to assess the emails for each account. A poor reputation can be caused by a number of things, and it's typically not as simple as one factor influencing the reputation. If you have a high bounce rate or spam complaints, those are some of the reasons for a poor reputation, but aren't the only factors Mandrill uses. The reputation system is continuously monitored to ensure that it serves the purpose of helping to prevent spam.
Paid vs. free accounts
The initial hourly quota is higher for paid accounts, but as Mandrill learns about sending, may be adjusted up or down. Paid and free accounts with poor reputation may see their hourly quota drop below the initial quota. The reputation of an account is not based on whether you've paid for your plan - it's entirely based on the email you're sending.
Going over the hourly quota
If you send more than your quota in an hour, we won't delete the mail - we'll just queue it until the next hour and then deliver it. By then your quota will likely have increased as we respond to your increased volume.
Account reputation and the hourly sending quota are handled automatically as you send email and Mandrill learns about the emails you're sending.