Email usage
Sendmux charges email usage from the team balance.
For outgoing mail, each provider-accepted To, CC, or BCC recipient occurrence is billed. Addresses rejected before provider acceptance are not charged.
If the same address appears in more than one recipient field, each provider-accepted occurrence is billed separately.
Inbound usage is counted when a message is accepted into a mailbox. Mail rejected by mailbox allow or block rules is not billed.
Usage transactions can be grouped, so the transaction table may show one Incoming email usage line for several received messages in a short period.
Balance
The Billing page shows current balance, purchased amount over the last 30 days, and consumed amount over the last 30 days. If balance is too low, sending requests can fail withinsufficient_credits. Top up before retrying.
Manual top-up
Choose a top-up amount, then complete checkout. Supported amounts are:Auto top-up
Auto top-up adds balance when your team drops below a threshold.
Use a monthly limit that covers expected usage but still caps unexpected spend.
Low-balance alerts
Low-balance alerts email you when team balance drops below the selected threshold.Transactions
The transaction table shows balance movements with type, amount, date, and description. Use it to reconcile purchases, auto top-ups, usage, refunds, and manual adjustments.API access
Use the Management API to read balance, summary, and transaction history from your own reporting tools.Management API
Open the generated Billing endpoint reference.
Related guides
Send by HTTP
Handle
insufficient_credits on sending requests.Team limits
See which limits are separate from balance.
Mailboxes
Use sender rules to reject unwanted inbound mail before it is billed.
API keys
Create keys for billing reporting.