> ## Documentation Index > Fetch the complete documentation index at: https://sendmux.ai/docs/llms.txt > Use this file to discover all available pages before exploring further. # Use Sendmux with MailWizz for cold email outreach > Connect MailWizz to Sendmux, set humanised sending limits, and run cold email outreach campaigns with scheduled follow-ups and signed feedback. Connect MailWizz to Sendmux when you want MailWizz to manage prospects, campaign content, schedules and follow-ups while Sendmux manages eligible sending accounts, routing and sending limits. You configure one Sendmux delivery server in MailWizz, then use it across your outreach sequence. MailWizz campaign messages passing through Sendmux to several eligible sending accounts, with delivery feedback returning to MailWizz Before you start, use MailWizz 2.0.34 or later. You also need a Sendmux team with an active sending account and a publicly reachable MailWizz frontend URL using HTTPS. ## Set up MailWizz with Sendmux Download the latest Sendmux extension. In the MailWizz backend, open **Extend** → **Extensions** → **Upload extension**, upload the archive and enable **Sendmux Sending API**. MailWizz upload extension dialog with a ZIP archive chooser and Upload archive button In Sendmux, open **API Keys**, create a send-capable mailbox key and copy the reveal-once value beginning with `smx_mbx_`. In MailWizz, open **Delivery servers** → **Create new**, select **Sendmux Web API**, paste the key into **Sending Key** and complete the sender fields. Save the server. It remains inactive until you connect signed feedback. Reopen the server and select **Info** to copy its webhook URL. In Sendmux, open **Webhooks** → **Create webhook**, use that URL and subscribe to `message.bounced` and `message.complained`. Copy the reveal-once `whsec_` secret back into **Webhook signing secret** in MailWizz. Save, test and activate the delivery server. In Sendmux, open **Accounts** → **Add Account**. Add each account you want in your outreach pool, complete its connection details and run the available test. Sendmux Add Account panel showing the available sending account connection types Set accurate From and Reply-To details for each account. Then configure fixed limits or minimum-to-maximum ranges for supported per-second, per-minute, per-hour and per-day windows. Sendmux quota fields for per-second, per-minute, per-hour and per-day sending limits Choose limits that fit the account's history and provider policy. A range such as `5–10` lets Sendmux periodically select an active cap inside those boundaries. Messages above the current cap wait until capacity is available. Create a regular MailWizz campaign for your prospect list. Choose the audience, write the message and complete the normal scheduling steps. MailWizz campaign actions for scheduling the campaign, staying on the page or saving changes Build each follow-up as a separate MailWizz autoresponder campaign, triggered after the original campaign is sent or opened. Set the delay and time unit deliberately, then read the full sequence as the recipient before activation. Use a separate campaign for every intended follow-up. Both the original campaign and its follow-ups use the same Sendmux delivery server, so account eligibility and sending limits continue to apply. Send only to people you may lawfully contact. Keep your targeting relevant, identify the sender accurately, honour suppression records and provide a clear way to stop further contact. ## How MailWizz and Sendmux divide the work MailWizz owns the campaign workflow. Sendmux decides which eligible account can send and enforces that account's current limits. This keeps lists and automations in MailWizz without recreating every sending account as a separate delivery server. | MailWizz | Sendmux | | ------------------------------------- | ------------------------------------- | | Lists, subscribers and segments | Connected sending accounts | | Campaign content and schedules | Account eligibility and routing | | Autoresponder conditions and delays | Per-second, minute, hour and day caps | | Campaign bounce and complaint actions | Signed bounce and complaint events | ## Choose fixed limits or ranges Use a fixed cap when you want one predictable ceiling. Use a range when the active ceiling may move within approved boundaries. Sendmux selects a value when account information refreshes and keeps that cap until the next refresh. A range varies the sending ceiling. It does not add a random delay to each message or guarantee inbox placement. Good targeting, authenticated sender domains, relevant content and a healthy account history still matter. ## How feedback returns to MailWizz The extension includes MailWizz campaign and subscriber identifiers with campaign sends. When Sendmux reports a bounce or complaint, MailWizz verifies the signed event and matches it to the campaign, subscriber and delivery server that recorded the send before changing subscriber state. | Sendmux event | MailWizz result | | ------------------- | ----------------------------------------------------------------- | | Permanent bounce | Records a hard bounce and normally blacklists the subscriber. | | Transient bounce | Records a soft bounce. | | Undetermined bounce | Records an internal bounce. | | Complaint | Applies MailWizz feedback handling and blacklists the subscriber. | Invalid, unsigned or unmatched webhook calls cannot alter campaign records. If a later bounce has a stronger classification, the extension preserves that stronger result. ## What `queued` means `queued` means Sendmux accepted the message for processing. It does not mean the recipient system accepted it or that it reached the inbox. Final delivery still depends on the selected account, the recipient system, message quality and sender reputation. ## Check before your first campaign * Test and activate the Sendmux delivery server in MailWizz. * Confirm at least one eligible sending account is active. * Review From, Reply-To and sending limits for every account. * Confirm the feedback webhook has its saved `whsec_` secret. * Check prospect sourcing, suppression and opt-out handling. * Read the original campaign and every follow-up from start to finish. Start with a controlled campaign. Check delivery logs, bounces, complaints and replies before you raise volume. ## Common questions Not for campaign feedback handled by this integration. The signed webhook writes correlated bounces and complaints into MailWizz. Keep it active and monitor failed webhook deliveries in Sendmux. Yes. Add each account to Sendmux and configure its sender details, limits and routing. Sendmux chooses among eligible active accounts for the key used by the MailWizz delivery server. A new server remains inactive until its webhook signing secret is saved. MailWizz also deactivates it after a credential change so you can test the new configuration before campaigns use it. Use a separate MailWizz campaign for each intended follow-up. Deliberately re-entering the same subscriber into the same autoresponder during the Sendmux idempotency window is not supported. ## Related guides Add accounts and configure sender defaults, limits and routing. Keep selected sending accounts together for a chosen traffic stream. Review message status and investigate delivery activity. Monitor bounce rates, complaint rates and account health.