Suppressions and deliverability

The suppression list

Each account has a suppression list. If all recipients on a send are suppressed, nothing leaves Duta and the response says suppressed. If a send has multiple recipients and only some are suppressed, the suppressed ones are dropped and the rest are queued as normal.

Addresses join the list on their own:

Reason	Added when	Can you remove it?
hard_bounce	The address does not exist or refused permanently.	No
complaint	The recipient marked your mail as spam.	No
unsubscribe	The recipient used the unsubscribe link.	No
manual	You added it, in the dashboard or with POST /v1/suppressions.	Yes

The first three are permanent on purpose. Mailing an address that does not exist, or a person who asked you to stop, is what gets a sender blocked by mailbox providers. Removing one is refused with 403.

Manage suppressions

Add an address by hand:

curl -X POST https://api.duta.indra.sh/v1/suppressions \
  -H "Authorization: Bearer $DUTA_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{ "email": "user@example.com" }'

Remove a manual entry:

curl -X DELETE "https://api.duta.indra.sh/v1/suppressions/user%40example.com" \
  -H "Authorization: Bearer $DUTA_API_KEY"

The email in the URL path must be URL-encoded. Attempting to delete a permanent suppression is refused with 403.

List and search the list with GET /v1/suppressions?q=&limit=. Suppressions page with after set to the email address cursor.

Your reputation

Mailbox providers judge a sender by its bounces and complaints. Duta shares sending infrastructure between accounts, so it watches each account and acts early, well before any provider would:

Over the last 24 hours	Bounce rate	Complaint rate
Warning by email	2%	0.05%
Daily volume drops a step	3%	0.08%
Sending paused for review	5%	0.1%

Rates are measured once an account has sent at least 200 emails in the window. Below that, a few bounces are noise, not a trend.

A paused account gets an email saying why. To keep clear of these levels:

• Send only to people who asked for the mail, such as the buyer who just placed an order.
• Remove addresses that bounce. Duta does this for you through the suppression list.
• Keep marketing mail out of Duta entirely.
• Check new sign-up addresses before you send to them.