Daily limits and sending windows

Who this is for: anyone who wants steady sending without hurting their sender reputation, and anyone wondering why a campaign is sending slower than expected.

Swift Outbox sends slowly on purpose. Spam filters watch for mailboxes that suddenly send a lot, at night, at machine-like intervals. Three layers of limits keep you safe, and the lowest one always wins.

The three layers

Your plan also has emails-a-day and emails-a-month limits. See Plans, credits and upgrades.

Example: two campaigns each set to 30 a day, with a total daily limit of 40, send at most 40 emails a day between them.

Set a campaign’s sending window

In the campaign editor, step 4 Sending rules:

1. Daily sending limit: start at 20 to 30 emails a day.
2. Send on: pick the days. All seven are on by default; most B2B campaigns use Monday to Friday.
3. Send between: the default is 09:00 to 17:00. The window cannot run overnight, so the end time must be after the start time.
4. Time zone: leave it on Workspace time zone, or pick your leads’ time zone if they are elsewhere.
5. Wait between emails: a random wait, 5 to 15 minutes by default. The longest wait must be at least the shortest.
6. Send from: All enabled accounts, or Choose accounts to use only some.

Note: Send at any time of day removes the time window. Emails still go out only on the chosen days. The app warns you that emails sent at night are more likely to be flagged as automated, and business hours usually get more replies.

Safe numbers for new mailboxes

There is no automatic warm-up in the app, so raise limits by hand:

1. Week 1: 20 emails a day per account.
2. Each following week: add about 10 a day, as long as bounces and spam complaints stay low.
3. Stop around 50 a day per account for Gmail and Outlook mailboxes. To send more, add more sending accounts rather than pushing one account harder.

Tip: Ten accounts at 30 a day send 300 emails a day and look far more natural than one account at 300.

Automatic pause

The app protects your mailboxes. After at least 20 emails, a campaign pauses by itself when:

• 5% or more bounce. Verify the list before you resume, or your mailbox reputation suffers.
• 0.3% or more are marked as spam. Review the message and the list before you resume.

A sending account that fails 5 times in a row is also turned off. See Connect a sending account.

Common mistakes

• Expecting the campaign limit to override the account limit. The lowest limit wins. A campaign set to 100 a day, sending from one account limited to 50, sends 50.
• A window that is too narrow. 09:00 to 10:00 with a 5 to 15 minute wait sends only about six emails per account each day.
• Forgetting the time zone. A 09:00 to 17:00 window in your time zone may be the middle of the night for leads abroad.

Next step

Prove to inbox providers that your emails are really from you: Domain authentication: SPF, DKIM and DMARC.