Definition
SMS marketing sends promotional or transactional messages via text message (SMS or MMS) to opted-in subscribers. Email marketing sends messages to email inboxes. While both are direct communication channels, they differ fundamentally in reach, cost, engagement patterns, and content capability.
Many businesses use both channels together in an integrated strategy, using SMS for urgent or high-priority messages and email for detailed content, nurturing, and automation.
Email vs SMS Comparison
| Factor | Email Marketing | SMS Marketing |
|---|---|---|
| Reach | 4.3 billion users | 5.6 billion users |
| Open rate | 15-30% | 90-98% |
| Median open time | Hours to days | Within 3 minutes |
| Click-through rate | 2-5% | 15-35% |
| Average cost per send | 0.1-0.5p | 3-10p |
| Content length | Unlimited | 160 characters (SMS) |
| Rich media | Images, video, interactive | Links only (MMS can include images) |
| Deliverability | Complex (spam filters, authentication) | Simple (carrier-dependent) |
| Opt-out rate | Low | Higher |
| Best for | Nurturing, education, automation | Urgent alerts, offers, reminders |
When to Use Each Channel
| Scenario | Best Channel | Reason |
|---|---|---|
| Welcome series | Richer content sets expectations | |
| Flash sale | SMS | Immediate delivery guarantees high visibility |
| Abandoned cart | Both | Email first, SMS escalate if no action |
| Newsletter | Content depth and formatting matter | |
| Order confirmation | Receipt detail needs space | |
| Shipping update | SMS | Real-time tracking benefits from instant delivery |
| Re-engagement | More space to persuade | |
| Appointment reminder | SMS | Immediate read rate ensures they see it |
| Educational content | Long-form content impossible via SMS | |
| Loyalty programme | Both | Coordinated cross-channel experience |
How to Build an Integrated SMS and Email Strategy
- Use email for depth and SMS for urgency: Send detailed content by email. Reserve SMS for time-sensitive messages that need immediate attention.
- Let subscribers choose their channel: Offer preference centre options for email, SMS, or both. Never add SMS without explicit consent.
- Coordinate timing: If a subscriber does not open an email within 2 hours, send an SMS version. This escalation pattern respects their inbox while ensuring delivery.
- Maintain consistent branding: Both channels should use the same tone, offers, and visual identity where possible.
- Track cross-channel attribution: Measure how SMS influences email engagement and vice versa.
Related Glossary Terms
A/B Testing
A/B testing in email marketing is the practice of sending two variations of an email to a small sample of your list to determine which version performs better before sending the winner to the remaining subscribers.
Abandoned Cart Email
An abandoned cart email is an automated message sent to customers who added items to their online shopping cart but left without completing the purchase. It is one of the highest-converting email types in ecommerce.
AIDA Model for Email
The AIDA model (Attention, Interest, Desire, Action) is a classic copywriting framework used to structure email campaigns that guide subscribers from awareness to conversion.
AMP for Email
AMP for Email is a Google-developed framework that allows email messages to include interactive elements like forms, carousels, accordions, and live content. It turns static emails into dynamic, interactive experiences directly inside the inbox.
Announcement Email
An announcement email is a dedicated campaign that communicates a specific update, milestone, or change to subscribers, from product launches and feature releases to company news and events.
AOL Mail for Email Marketers
AOL Mail is a legacy email provider with specific deliverability requirements and rendering quirks, now operating as part of the Yahoo+AOL network under shared infrastructure.
Frequently Asked Questions
Yes. SMS costs 10-50 times more per send than email. A typical email campaign costs 0.1-0.5p per send. SMS costs 3-10p per message. However, SMS open rates are significantly higher, so the cost per engaged user may be comparable depending on your audience.
Yes, in most regions. Consent for email does not cover SMS and vice versa. You must collect separate opt-ins for each channel and provide separate opt-out mechanisms. Combining consent is a compliance risk under GDPR, PECR, and similar regulations.
Many email service providers including Klaviyo, Mailchimp, and HubSpot offer integrated SMS capabilities. These integrations share subscriber profiles across channels and support cross-channel automation triggers.
There is no universal ideal ratio, but a common approach is 1 SMS for every 5-10 emails. SMS should be reserved for high-value, time-sensitive messages. Email can carry the majority of your regular communication. A general guideline is no more than 2-4 SMS per month per subscriber.
Expect 20-40% overlap between your email and SMS lists if you market to both channels. Subscribers who opt into both channels are typically your most engaged audience and should receive coordinated, not duplicated, messaging.