How to Set Up a Multi-Channel Dunning Sequence (Email + SMS)

An email-only dunning sequence recovers about 40-50% of failed payments. Add SMS, and that number climbs to 55-70%. That difference isn't theoretical. It's documented across SaaS companies of every size, and the mechanism is straightforward: emails get buried, but text messages get read.

SMS has a 98% open rate. Email sits around 20-30% for transactional messages. When a customer's payment fails and they're not checking email (or your message lands in promotions/spam), an SMS cuts through.

This guide covers how to build a multi-channel dunning sequence that combines email and SMS for maximum recovery.

Why multi-channel recovers more

The math is simple. Not every customer responds to the same channel.

Some customers live in their inbox and act on emails within minutes. Others have 14,000 unread emails and will never see yours. Some respond to the first touch. Others need three or four. A multi-channel approach covers more of these scenarios.

Here's what the data shows:

• Email-only dunning: 40-50% recovery rate
• Email + SMS dunning: 55-70% recovery rate
• The lift from adding SMS: 15-25 percentage points

That lift comes from reaching customers who were unreachable via email alone. It's not that SMS is "better" than email. It's that the two channels reach different people at different moments. Combined, they cover more ground.

There's also a psychological component. A text message feels more personal and more urgent than an email. It signals that this is genuinely important, not a routine notification.

The recommended sequence

Here's a proven 14-day multi-channel sequence. Adapt the timing to match your grace period.

Day 1: Email #1 (Informational)

Channel: Email Purpose: Notify the customer about the failed payment. Tone: Friendly, helpful.

Content:

• What happened: "Your payment of [amount] didn't go through"
• Why it might have happened: expired card, insufficient funds, bank block
• What to do: single CTA button to update payment method
• What happens next: "We'll retry automatically, but you can fix it now"

This email should go out within 1 hour of the failure. Faster is better. The failure is fresh, and the customer may still be actively using the product.

Subject line examples:

• "Your [Product] payment didn't go through"
• "Problem with your card on file"

Day 3: Email #2 (Reminder)

Channel: Email Purpose: Follow up with customers who missed or ignored Email #1. Tone: Slightly more direct.

Content:

• Reiterate the problem: "We still haven't been able to process your payment"
• Add a deadline: "You have until [date] before your access is affected"
• CTA: update payment method
• Offer help: "If something's wrong, reply to this email"

Subject line examples:

• "Your card is still being declined"
• "[Name], your payment is still failing"

Day 5: SMS #1

Channel: SMS Purpose: Reach customers who aren't responding to email. Tone: Concise, direct.

[Name], your [Product] payment of [amount] failed. Update your card to keep access: [link]

Keep it under 160 characters if possible (one SMS segment). Include the customer's name, the product name, and a direct link to the payment update page.

This is the first SMS in the sequence. Placing it on Day 5 gives email two chances first. Customers who were going to respond to email have already done so. The remaining group includes people who haven't seen the emails or aren't motivated by email alone.

Day 7: Email #3 (Urgent)

Channel: Email Purpose: Escalate urgency. Make consequences clear. Tone: Direct, concerned but not aggressive.

Content:

• Clear deadline: "Your account will be suspended in 3 days"
• What they'll lose: list specific features or data access
• CTA: prominently placed update button
• Help offer: "Having trouble? We can help"

Subject line examples:

• "Final warning: your [Product] account is at risk"
• "Your access will be suspended in 3 days"

Day 10: SMS #2

Channel: SMS Purpose: Final push before suspension. Tone: Urgent, short.

Final reminder: Your [Product] access will be suspended tomorrow unless you update your card. [link]

This is the last SMS. It pairs with the urgency of the approaching deadline. Customers who've ignored everything up to this point get one more direct nudge on a channel they're likely to see.

Day 14: Email #4 (Suspension / Final)

Channel: Email Purpose: Notify about suspension. Offer a path back. Tone: Matter-of-fact, door left open.

Content:

• "Your account has been suspended"
• What that means: no access, but data is preserved for 30 days
• How to come back: single CTA to reactivate
• No hard feelings: "If you've decided to move on, no action needed"

Subject line examples:

• "Your [Product] account has been suspended"
• "We've paused your [Product] subscription"

Channel-specific best practices

Email best practices

Send from a recognizable address. Use something like [email protected] or [email protected]. Not noreply@ (it discourages replies and feels impersonal).

Keep emails short. Three to four paragraphs maximum. One CTA per email. The customer should grasp the problem and the action in under 10 seconds.

Design for mobile first. Over 60% of emails are opened on phones. Use a single-column layout, large CTA buttons (minimum 44x44px tap target), and readable font sizes (16px minimum body text).

Authenticate your domain. Set up SPF, DKIM, and DMARC for your sending domain. This directly affects deliverability. Without proper authentication, your emails are more likely to land in spam.

Use a dedicated sending domain or subdomain for transactional emails. This separates your dunning email reputation from your marketing email reputation.

Personalize. Use the customer's first name, the specific amount, and their card details (last four digits). Specificity builds trust and signals that this is a real, relevant notification.

SMS best practices

Keep messages under 160 characters. One SMS segment. Longer messages get split and may arrive out of order or feel overly long for a text.

Always include a direct link. The link should go straight to the payment update page, not a homepage or login screen. Use a URL shortener if needed, but prefer your own branded short domain over generic shorteners (which can trigger spam filters).

Identify yourself immediately. Start with the product name or your company name. Customers need to know who's texting before they'll click anything.

Limit to 1-2 SMS per sequence. SMS is high-impact but high-intrusion. More than two text messages about a billing issue crosses from helpful to annoying. Reserve SMS for the moments where it matters most.

Send during reasonable hours. 9 AM to 8 PM in the customer's local time zone. A text at 2 AM about a billing issue is a negative experience regardless of the content.

Respect opt-outs immediately. If a customer replies STOP, remove them from SMS instantly. This is both a legal requirement and a trust issue.

Compliance requirements

Multi-channel dunning involves two regulatory frameworks you need to understand.

CAN-SPAM (Email, US)

CAN-SPAM applies to commercial emails. Dunning emails are generally considered transactional (they're about an existing business relationship and a pending transaction), which gives them more flexibility than marketing emails. But you should still:

• Include your physical mailing address
• Provide a working unsubscribe mechanism
• Use accurate "From" and subject lines
• Not use deceptive headers

Transactional emails don't require opt-in consent under CAN-SPAM, but providing an unsubscribe option is good practice and builds trust.

TCPA (SMS, US)

The Telephone Consumer Protection Act regulates text messages. The rules are stricter than email:

Prior express consent is required before sending SMS. For transactional messages (which dunning notifications generally are), you need at least "prior express consent," which means the customer knowingly provided their phone number to you in the context of the business relationship.

Written consent is required for marketing SMS. If your dunning messages include any promotional content (upsells, discount offers), they may be reclassified as marketing, requiring prior express written consent (typically via a checkbox or digital signature).

Opt-out mechanism: Include instructions to opt out (e.g., "Reply STOP to unsubscribe") in at least the first message. Honor opt-outs immediately.

Reasonable hours: While there's no explicit TCPA restriction on timing, sending during reasonable hours (9 AM - 9 PM local) is an established best practice that avoids complaints.

GDPR (EU/UK)

If you serve customers in Europe:

• You need a legal basis for processing their phone number for billing communications (legitimate interest or contractual necessity both apply)
• You must be transparent about how you use their data
• You must provide easy opt-out
• You must honor data deletion requests

Practical steps

1. Add a phone number field to your signup or billing form with clear language: "We may use this number to contact you about billing issues"
2. Store consent records (when and how the customer provided their number)
3. Include opt-out instructions in your first SMS
4. Process opt-outs in real time
5. If you're unsure about your specific situation, consult a lawyer familiar with TCPA/GDPR

How to collect phone numbers

SMS only works if you have the customer's phone number. Here's how to build your phone number coverage over time.

At signup

Add an optional phone number field to your registration form. Label it clearly: "Phone number (for account notifications)." Making it optional avoids friction in the signup flow while still capturing numbers from willing customers.

Typical collection rate at signup: 20-40% when the field is optional.

During onboarding

After signup, during the onboarding flow, prompt for a phone number. Frame it as a benefit: "Add your phone number so we can text you if there's ever an issue with your billing." A well-placed prompt during onboarding can push coverage to 40-60%.

In account settings

Ensure there's a clear phone number field in your account settings or billing page. Some customers will add their number organically as they explore the product.

During the dunning sequence itself

This is counterintuitive but effective. In your second or third dunning email, include a line: "We tried to reach you by email, but haven't heard back. Add your phone number so we can send a quick text reminder next time." You won't collect a number for the current failure (the sequence is already in progress), but you'll build coverage for future failures.

Realistic expectations

You won't get 100% phone number coverage. A realistic target for a B2B SaaS is 40-60%. For B2C, 50-70%. The remaining customers receive email-only dunning, which is still effective. Multi-channel is a lift on top of the email baseline, not a replacement for it.

Fallback: when you don't have a phone number

For customers without a phone number on file, the sequence should gracefully degrade to email only. Don't skip touchpoints entirely; replace SMS with additional or differently timed emails.

Modified sequence for email-only customers:

• Day 1: Email #1 (same)
• Day 3: Email #2 (same)
• Day 5: Email #3 (an additional email that would have been the SMS touchpoint)
• Day 7: Email #4 (urgency email, same content as the multi-channel Day 7 email)
• Day 14: Email #5 (suspension notice)

The email-only sequence has more emails because it's compensating for the missing channel. This is still better than the standard 3-email sequence most companies default to.

Setting up in Rekko

If you're using Rekko, the multi-channel setup is straightforward:

1. Connect your Stripe account via OAuth
2. Create a sequence in the Sequences section
3. Add steps for each touchpoint, selecting either Email or SMS as the channel
4. Configure timing (delay from trigger) for each step
5. Write your messages using the template editor with variables like {{customer_name}}, {{amount}}, and {{payment_link}}
6. Set your grace period in settings
7. Activate the sequence

Rekko handles the logic for falling back to email-only when no phone number is available, managing opt-outs across channels, and tracking recovery by channel so you can see the impact of each touchpoint.

Measuring multi-channel performance

After running your multi-channel sequence for at least a month, review these metrics:

Overall recovery rate: Compare to your previous email-only rate. You should see a 15-25 percentage point lift.

Recovery by channel: What percentage of recoveries happened after an email vs after an SMS? This tells you the incremental value of each channel.

Recovery by touchpoint: Which specific step (Email #1, SMS #1, Email #3, etc.) drives the most recoveries? The first email typically recovers 25-35% on its own. SMS typically adds another 10-15%.

SMS opt-out rate: Track how many customers opt out of SMS. Below 2% per message is normal. Above 5% suggests your messages are too frequent or poorly timed.

Time to recovery: Multi-channel sequences typically recover payments faster because SMS accelerates customer action. Measure whether your average time to recovery decreased.

The data tells you what's working. If SMS on Day 5 recovers 12% of remaining failures, it's worth the cost. If SMS on Day 10 only recovers 2%, you might simplify by removing it. Test, measure, optimize.

Multi-channel dunning isn't complicated. It's email sequences you're probably already running, plus one or two well-timed text messages. The lift in recovery rate makes it one of the highest-ROI additions to your payment recovery workflow.