Getting your email to the person it was meant for is fundamental to how a business runs, and understanding the delivery statuses is how you both achieve that and troubleshoot it when it fails.
Sending does not always end in delivery. When an emailed document runs into trouble, Invoice Office tells you: the status appears on your homepage and on the document overview pages, so a failed invoice does not sit silently unpaid while you assume it arrived.
Here is what each status means.
Dropped
A drop means our system prevented your email from being sent at all — it is not a deliverability problem, because nothing was ever attempted. Each drop comes with a specific reason so you can diagnose it. The common ones:
- Spam content detected. If the integrated spam checker app is enabled, an email identified as containing spam is dropped before sending. That protects your sender reputation and keeps deliverability high for your legitimate mail.
- Previous unsubscription. If the recipient has unsubscribed from your communications, new emails to them are dropped automatically. This respects their preference and keeps you compliant.
- Invalid recipient email. Less common as a drop — a bad address usually surfaces as a bounce, after a delivery attempt — but a fundamentally malformed address can fail initial validation and be dropped instead.
A drop is worth acting on immediately, because nothing about it resolves on its own. Watching which reasons come up lets you refine how you send and stop losing messages before they leave.
Deferred
Deferred means the receiving server has not accepted the message yet, but has not refused it either — a temporary network problem, a busy recipient server, or a full inbox. We do not give up: delivery is retried for up to 72 hours. That persistence is why most deferrals arrive in the end without you doing anything.
What happens after 72 hours?
If the message still cannot be delivered once the retry window closes, the status changes: a deferred message becomes a block, meaning it is permanently undeliverable. That is your signal to correct the address rather than keep sending to it.
Spam report
A spam complaint is a signal you cannot afford to ignore. Most Internet Service Providers offer a feedback loop (FBL) — a mechanism that relays a specific complaint from one of their users back to the email service provider that sent it. When we receive that notice, we raise a spam event on your account.
That event matters for three reasons:
- Prompt reaction. You find out immediately that someone marked your email as spam, in time to adjust the content, the audience, or how often you send.
- Preventing future complaints. You can stop sending to that address right away. Continuing to mail someone who has complained damages your sender reputation and pushes your other messages toward the spam folder.
- Sender health. ISPs watch complaint rates closely. A high rate gets your mail throttled or blacklisted, which affects every recipient, not just the one who complained.
Responding to spam events keeps your list clean and your messages landing where people can act on them.
Bounce
A bounce is caused by a problem with the recipient’s address. The frequent culprits:
- Outdated addresses. People change jobs and providers, or abandon an account.
- Typos. A missing character, an extra dot, the wrong domain.
- Non-existent accounts. The address simply does not exist on the recipient’s server.
You usually cannot tell an address is dead until it bounces — which is exactly why the event is useful. It confirms which addresses are no longer valid, and removing them keeps your records accurate. It also protects deliverability: repeatedly mailing invalid addresses signals careless sending, while a clean list signals a responsible sender and improves the odds your legitimate mail reaches the inbox.
What to do with them
- Dropped or bounced — fix the address on the customer record before you chase payment. Chasing an invoice that never arrived wastes the call.
- Deferred — wait. It is still being retried, and most deferrals resolve themselves.
- Spam report — stop sending to that address, and treat repeated reports as a signal to check what your emails look like on arrival.
If deliverability is a recurring problem, sending through your own mail server and domain is the bigger fix — it puts your sender reputation in your own hands.