One of the earlier conversations on a new SFMC engagement usually includes the client asking for a way to "grow the list fast." The worst answer is to buy a list from a data broker. The second-worst answer is "we'll add a newsletter form to the website footer." Neither of those does what the client hopes.
Here's what the data actually says about acquisition channels and which ones are worth building infrastructure around.
Effectiveness by channel
Salesforce's own research on what marketers use versus what actually works shows a huge mismatch:
| Channel | % of marketers using | Effectiveness rating |
|---|---|---|
| Inbound sales calls | 23% | 71% |
| Mobile sign-up | 12% | 59% |
| Social media (Facebook/LinkedIn Lead Forms) | 39% | 59% |
| Inbound service calls | 23% | 63% |
| In-store promotions | 20% | 57% |
| Website sign-up | 74% | 42% |
The takeaway jumps off the page: website sign-up is the most-used channel and the lowest-converting one. Inbound calls are the highest-converting and among the least-used. If you're advising a client on acquisition strategy, don't start with "let's add a form to the website" - that's the default every competitor is already using badly.
How to implement each channel in SFMC
Website sign-up (the default everyone already has)
Use Smart Capture inside CloudPages, or embed a form that writes to a Data Extension via API.
Best practices that usually get skipped:
- Offer a clear incentive ("10% off your first order for signing up").
- Do not pre-check the opt-in checkbox.
- Use a CAPTCHA to stop bot signups - bots quietly inflate the list with addresses that never open.
Mobile app sign-up
When a user creates an account in the app, add an explicit opt-in checkbox for email. Don't assume account creation means marketing consent - GDPR and good sense both disagree.
For SMS-first funnels: the user texts a keyword to a short code, Mobile Studio triggers a welcome automation that also captures email. Email Studio and Mobile Studio can work together here.
Social - Facebook and LinkedIn Lead Forms
Both platforms have native lead forms that submit without the user leaving the app. Conversion is substantially higher than sending traffic to an external landing page.
Data flows into SFMC via Advertising Studio (Facebook Custom Audiences integration) or via API. Set up an Automation to process new leads within 5 minutes of submission - the window to engage a hot lead is very short.
In-store promotions
Cashier asks the customer "can I get your email for the receipt and promotions?" - one of the highest-consent channels because there's a face-to-face trust moment.
The trap: cashier typos. Customer says "john.smith@gmail.com," cashier types "jon.smtih@gmai.com," garbage into the DE. Always use Double Opt-In on this channel. The consent email will bounce on a typo, and the record stays out of the active list.
Better pattern: print a QR code or short URL on the receipt / in-store signage. Customer fills the form on their phone. No cashier typing, cleaner consent, slightly better conversion.
Inbound sales and service calls
The most underused + most effective channel. When a customer calls, they're actively engaging. Asking "would you like to receive product updates and offers by email?" at the end of a successful call gets a high yes rate.
Implementation: the agent checks a box in the CRM. Marketing Cloud Connect syncs that Contact's opt-in flag into SFMC, which triggers a welcome automation.
The don't-do list
DO NOT buy subscriber lists, even ones labeled "GDPR-compliant."
-> Those subscribers never opted in to your client's brand.
-> High complaint rate, IP reputation damaged, deliverability tanks.
DO NOT pre-check opt-in boxes.
-> Not valid consent under GDPR.
-> Bad-faith signal that marketing regulators watch for.
DO NOT force email opt-in to complete a purchase.
-> Transactional email is fine. Marketing email needs explicit consent.
DO NOT scrape email addresses from websites, LinkedIn, forums.
-> No consent, violates platform ToS, possibly violates local law.
DO NOT re-import unsubscribed contacts.
-> Violation of CAN-SPAM / GDPR.
Client says "grow the list fast" - the evaluation
When a client pushes you toward a shortcut, run the list source through this screen before importing anything into SFMC:
- Does the subscriber know they will receive marketing email from this specific brand?
- Did the subscriber actively opt in (not pre-checked)?
- Is there proof of consent stored (timestamp, source, method)?
- Does the list source comply with GDPR / CAN-SPAM / PDPA as applicable?
- What would the bounce rate and complaint rate look like if this list received a send tomorrow?
Any "no" answer = do not import. The cost of a bad import is weeks of deliverability recovery and possibly a blocked sending IP.
Takeaway
Acquisition is a long game. The channels that pay off over 2 years are the ones that source subscribers who actually want to hear from the brand. Help the client build the higher-effectiveness channels (inbound calls, mobile, social lead forms) even though website sign-up is where everybody starts. 6 months in, the list will be smaller but the revenue-per-subscriber will be dramatically higher.
Building an SFMC acquisition stack? Our Salesforce team sets up CloudPages forms, API integrations, and CRM sync on production engagements. Get in touch ->
See our full platform services for the stack we cover.
