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Use this guide to connect Gmail, Google Workspace, Outlook, or Microsoft 365 accounts that Sendmux will use for sending. For a large account pool, import the account list first, then authorise each pending account from its row.
You need permission to manage sending accounts in Sendmux and sign-in access to every account you connect. If your organisation blocks third-party apps, ask a Google Workspace or Microsoft Entra administrator to complete the relevant preparation step below.

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Permissions Sendmux requests

Sendmux requests only the permissions needed to identify the account, keep the connection active, and send email. The connection also requests basic identity scopes so Sendmux can confirm which account completed the flow. Microsoft includes offline_access so the account can remain connected without an interactive sign-in for every send. Connected accounts always send from the mailbox address that completed authorisation. You can set a sender display name and reply-to address, but a different From Email address requires a separately authorised account.
Sendmux does not need permission to read, change, or delete mailbox content. Cancel the flow and contact Sendmux support if a provider prompt asks for Mail.Read, Mail.ReadWrite, IMAP access, or permission to read and permanently delete Gmail messages.

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Prepare Google Workspace

Most organisations can skip this section. Complete it only when a Workspace policy blocks third-party apps or requires an administrator to configure them first.
1

Open Google app access controls

In the Google Admin console, open Security > Access and data control > API controls, then select Manage App Access.
2

Configure Sendmux

Select Configure new app, search for Sendmux, and choose the Sendmux OAuth app. Select the organisational units whose accounts will connect.
3

Limit access to the required Google data

Choose Specific Google data. Allow the Google sign-in scopes and the Gmail scope described as Send email on your behalf. Finish and review the configuration before continuing.
Google says changes can take up to 24 hours, though they often apply sooner. See Google’s app access guide for current administrator roles and controls.
Administrator configuration allows the Sendmux app to request the approved scopes. It does not connect every mailbox or give Sendmux domain-wide access. Each account owner still completes the Sendmux authorisation flow.

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Prepare Microsoft 365

Most Microsoft 365 organisations allow the delegated Mail.Send permission without a separate administrator step. If your tenant blocks user consent, approve Sendmux once before connecting the account pool.
1

Open Microsoft account setup in Sendmux

Open Accounts, select Add Account, then choose Outlook / Microsoft 365.
2

Open the administrator flow

Expand Organisation requires admin approval? and select Open Admin Consent Page.
3

Review and approve

An authorised Microsoft Entra administrator signs in and reviews the delegated permissions. The sending permission must be Microsoft Graph Mail.Send. Approve only if the prompt matches the permissions described on this page.
4

Return to the account list

Close the administrator tab after approval. Each account can now complete its own Authorise flow.
Tenant-wide consent allows users in the organisation to connect Sendmux. It does not connect their mailboxes automatically. See Microsoft’s tenant-wide consent guide for current administrator roles and consent controls.

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Connect one account

1

Choose the account type

Open Accounts, select Add Account, then choose Gmail or Outlook / Microsoft 365. For Microsoft, keep Global (Commercial) selected.
2

Start the provider flow

Select Connect Account. Sign in to the exact account you intend to add.
3

Review the permission

Confirm the account address and the sending-only permission, then approve the connection. New Google Workspace accounts may first show Google’s welcome page. Complete that page, then restart the connection from Sendmux.
4

Confirm the result

Sendmux returns to Accounts. The account should show Active. If the provider rejected or cancelled the flow, use Authorise or Re-authorise beside the account to try again.

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Connect a large account pool

Importing creates the account records in one operation. Provider sign-in still happens once per account because each mailbox receives its own revocable OAuth credential.
1

Prepare the import file

Open Accounts > Accounts > Import Accounts, then select Download template. Keep the header row unchanged.Fill at least these columns for each connected account:You can also set its delivery group, sender display name, reply-to details, quotas, and routing weight in the same file. Sendmux ignores from_email for connected accounts and uses oauth_user_email as the sender address.
2

Import the accounts

Upload the file, review accepted and rejected rows, then select Import. New Google and Microsoft accounts appear as Pending because imported files never contain connected-account credentials.
3

Work through pending accounts

Filter the account list by Pending. Select Authorise beside the first account, verify the email address at Google or Microsoft, and complete the provider flow. Repeat for the remaining accounts.
4

Check the pool

Remove the Pending filter and confirm every connected account is Active. Review any Error row and use Re-authorise after correcting the provider-side issue.
Prepare Google or Microsoft administrator consent before starting a large batch. This removes organisation-policy interruptions, while keeping each mailbox connection separate and revocable.

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Troubleshooting

Pending is expected until that account completes OAuth. Select Authorise beside the account. If the action is not visible, confirm that your Sendmux role can manage sending accounts, then refresh the page.
Do not continue through Advanced. The expected Gmail permission is Send email on your behalf. Cancel the flow and contact Sendmux support with the team, account address, and time of the attempt.
Use Add Account > Outlook / Microsoft 365 > Organisation requires admin approval? > Open Admin Consent Page. After an authorised Entra administrator approves delegated Mail.Send, restart Authorise for the affected account.
Cancel the provider flow. Return to the matching account row and select Authorise again. Check the address shown by the provider before you approve access, especially when several accounts are signed in in the same browser.
Stop repeating the flow. Refresh Accounts and retry once from the account’s own Authorise or Re-authorise action. If the message returns, contact Sendmux support with the team, account address, and timestamp. This message is not a sending-account capacity limit.

Sending accounts

Import, configure, monitor, and route sending accounts.

Delivery groups

Route sending keys through a selected account pool.

Cold email outreach

Build a GTM sending pool with per-account caps.

Teams and access

Give operators the role they need to manage accounts.