Why did my Mailchimp Transactional (Mandrill) emails sent drop?
The Mailchimp Transactional (Mandrill) help pages give 5 common reasons. The first to rule out: When you send more than your quota allows, the extra emails wait in a backlog instead of going out right away.
Is it broken, or just quiet?
A number can fall because fewer people came, or because something stopped counting them. Below are the causes the Mailchimp Transactional (Mandrill) help pages give, and how to check each one yourself.
What causes it?
When you send more than your quota allows, the extra emails wait in a backlog instead of going out right away.
In the Mailchimp Transactional (Mandrill) help:
If you exceed your quota, unsent messages will be placed in the backlog.
Outbound Email, read 2026-11-12.Emails that wait in the backlog too long can be deleted without being sent, so a long backlog can lower your sent count for good.
In the Mailchimp Transactional (Mandrill) help:
Emails are only stored in the backlog for 48 hours; after that, they’re deleted from the account entirely.
Reputation and Rejections, read 2026-11-12.Your hourly quota can change with your account's reputation, so more failed sends can mean fewer emails allowed each hour.
In the Mailchimp Transactional (Mandrill) help:
The account’s reputation informs the account’s hourly quota, but it isn’t the only factor we use.
Reputation and Rejections, read 2026-11-12.Emails to addresses on the denylist are rejected rather than sent, so a growing denylist can lower your sent count.
In the Mailchimp Transactional (Mandrill) help:
The Rejection Denylist is the list of email addresses that Mailchimp Transactional will exclude from your sends.
Reputation and Rejections, read 2026-11-12.When your plan's monthly allowance runs out, new emails can be held instead of sent until more sending is available.
In the Mailchimp Transactional (Mandrill) help:
Monthly limit reached - You’ve sent all the emails your plan allows.
Outbound Email, read 2026-11-12.
How do I check it myself?
Check recent bounces alongside your sent count. Each bounced address can be rejected on later sends.
In the Mailchimp Transactional (Mandrill) help:
When an email bounces, the email address will be added to the Rejection Denylist.
Reputation and Rejections, read 2026-11-12.If you schedule emails ahead, expect them to show up on the day they go out, not the day you set them up.
In the Mailchimp Transactional (Mandrill) help:
A scheduled email counts towards the monthly send total at the time it’s sent, not when it’s scheduled.
Outbound Email, read 2026-11-12.Rejected emails do not come back later on their own, so a dip from rejections is not made up on a later day.
In the Mailchimp Transactional (Mandrill) help:
Messages that have been rejected cannot be resent
Outbound Email, read 2026-11-12.
How would I know the day it starts?
- Feder reads your emails sent and your unique clicks from Mailchimp Transactional (Mandrill) each day and compares each day with your own history.
- It tells you when emails sent go quiet or move outside their usual range.
Some numbers are too quiet to judge daily, such as a form filled in a few times a week. Until there is enough of your own history to judge a change, Feder says it is still learning and scores nothing, rather than guessing.
See what Feder reads from Mandrill, which feeds Reach. Feder only reads. It never changes anything in Mandrill.
What else goes wrong with these numbers?
- Why is Mailchimp Transactional (Mandrill) not sending my emails?Mailchimp Transactional (Mandrill)
- Why do my Mailchimp Transactional (Mandrill) unique clicks look wrong?Mailchimp Transactional (Mandrill)
- Why did Google Analytics stop collecting data?Google Analytics
- Why aren't my key events showing in Google Analytics?Google Analytics
- Why does Google Analytics show (not set)?Google Analytics
See every question.
Where do these answers come from?
Every cause and check on this page comes from the Mailchimp Transactional (Mandrill) help pages, quoted above with the date we read them. Last reviewed 2026-11-12. We read them again by 2027-11-12. If one changes, this page changes or comes down.