SendX add-ons fall into two categories: prepaid (fixed monthly/annual fee) and postpaid (usage-based charges at end of cycle). Understanding the difference helps you predict costs and manage your budget.
When you'll need this
Read this article if you're considering enabling an add-on and want to understand how you'll be charged, you want to predict your monthly costs, or you see usage-based charges on your invoice and want to understand them.
Prepaid add-ons (fixed fee)
Prepaid add-ons charge a set amount when you subscribe. You pay upfront for the billing period.
Examples of prepaid add-ons:
Add-on | Price |
Dedicated IP | $300/year ($25/month equivalent) |
Inbox Warmup (2k daily) | $200/month |
Inbox Warmup (5k daily) | $300/month |
Inbox Warmup (10k daily) | $400/month |
Live Warmup with Seeds | $200 per 1,000 daily warmup emails |
Inbox Testing | $25 per pack of 10 tests |
Elevated Support | $225 (3 calls) |
Professional Services | $525 per session |
How prepaid billing works:
You subscribe to the add-on
You're charged immediately (prorated if mid-cycle)
The add-on renews automatically each billing cycle
You can cancel anytime (cancellation takes effect at end of cycle)
You can view your prepaid add-on details in the Your Team Addons section of Team Billing:
Postpaid add-ons (usage-based)
Postpaid add-ons track your usage throughout the billing cycle and charge you at the end based on what you used.
Examples of postpaid add-ons:
Add-on | Pricing |
List Cleaning | $10 base + $0.003 per email verified |
Transactional Email | $10 base + $0.003 per email sent |
Threat Checks | $10 base + $0.005 per email checked |
How postpaid billing works:
You enable the add-on paying base fee upfront.
You use the feature throughout the month
Usage is tracked and visible in your dashboard
At the end of the billing cycle, you're charged for actual usage excluding base allowance.
Charges appear on your next invoice
Understanding Postpaid addon flow
Postpaid add-ons include a base allowance. For example, List Cleaning includes 1,000 verifications in the $10 base fee. After that, you pay $0.003 per additional verification.
Tracking your usage
You can see exactly how much you've used in the add-on details section. This helps you estimate your upcoming bill before the cycle ends.
Viewing your upcoming bill
Go to addon subscription card to see the breakdown of your upcoming charges, including base fees and overage costs.
This example shows usage of 8,999 verifications at $0.003 each, resulting in $27.00 in overage charges on top of the $10 base fee.
Can I have add-ons without a core plan?
Yes. You can enable add-ons even if you're on the free trial or haven't selected a contact tier yet. Add-on billing is independent from your core plan billing.
This is useful if you want to use a specific feature (like Inbox Testing) while still evaluating SendX.
When charges appear
Add-on Type | When You're Charged |
Prepaid | Immediately on subscription (prorated if mid-cycle) |
Postpaid | End of billing cycle, based on usage |
For postpaid add-ons, you can track current usage in your dashboard to estimate upcoming charges before the cycle ends.
Important notes
Add-ons auto-renew except one time purchase add-on. Unless you cancel, they renew each cycle.
Add-ons are per-team. If you have multiple teams, each team subscribes to and pays for its own add-ons.
Base fees apply to postpaid add-ons. List Cleaning has a $10 base fee that includes 1,000 verifications, plus per-email charges after that.
Common questions
Can I set a spending limit on postpaid add-ons?
SendX doesn't currently offer spending caps for postpaid add-ons. Monitor your usage regularly to avoid unexpected charges.
What happens if I don't use a prepaid add-on?
You're still charged the fixed fee. Prepaid add-ons are about access to the feature, not usage.
Are add-on charges shown separately on the invoice?
Yes. Your invoice breaks down core plan charges and add-on charges per team.
What's included in the base fee for postpaid add-ons?
For List Cleaning, the $10 base fee includes 1,000 email verifications. Any usage beyond that is charged at $0.003 per email.