Is an email marketing platform useful if users must connect their own SMTP provider?

Hi! A “bring your own SMTP” email marketing platform can absolutely be viable—but it’s usually a tougher sell for mainstream marketers unless you’re targeting a more technical audience (developers, agencies, privacy/IT-led teams) or positioning it as “we’re the campaign/automation layer, you choose the sender.” For many marketers, the requirement to connect and manage their own sending service does create friction around setup, deliverability responsibility, and consistent analytics, so it’s not a universal dealbreaker, but it narrows your market.

From the user’s perspective, here’s what typically feels good vs. risky:

Pros (why some users like BYO SMTP)

• Control & ownership of deliverability: They keep the sending reputation, dedicated IP/domain strategy, and can align sending with internal IT policies.
• Flexibility of vendor choice: They can use an SMTP relay or email API they already trust (or already pay for), and switch providers without rebuilding campaigns.
• Potential cost advantages at scale: If they already have a cost-effective sending provider, your platform can be “the marketing UI + automation,” not the delivery markup.
• Data/privacy preferences: Some teams prefer not to have another vendor handle delivery logs or message content beyond what’s necessary.

Cons (what makes it a dealbreaker for many marketers)

• Setup is harder and more failure-prone: SMTP configuration, authentication (SPF/DKIM/DMARC), bounce handling, complaint handling, and suppression lists are not things most marketers want to own.
• Deliverability becomes “their problem”: If inbox placement drops, they can’t just blame the email marketing platform—now they must diagnose sender reputation, IP warmup, throttling, spam complaints, blocklists, and provider-specific rules.
• Analytics can be less reliable unless you do extra work: Open rate and click tracking can still work, but bounce/complaint/unsubscribe events usually require provider event webhooks (or parsing bounce mailboxes), and different SMTP providers expose different event detail and timing.
• Workplace email providers are usually a bad fit for marketing: Google Workspace / Microsoft 365 mailboxes (and similar “employee email” systems) tend to have sending limits and anti-abuse protections that make them unsuitable for bulk newsletters or high-volume automations. Users may try anyway, then hit rate limits or spam-folder issues and blame your app.
• Compliance expectations don’t go away: Users will still expect one-click unsubscribe, suppression management, and permission-based list handling. If the SMTP provider doesn’t support marketing-friendly list-unsubscribe or feedback loops cleanly, the experience suffers.

A practical way to think about it: BYO SMTP is most accepted when it’s “BYO email sending provider designed for bulk/marketing,” not “use your work mailbox.” If your onboarding makes that clear, you avoid a lot of frustration.

If you want this model to feel “marketer-friendly,” the biggest product challenges to solve are:

• A guided setup that verifies SPF/DKIM/DMARC and warns about risky configurations
• Automatic bounce + complaint processing (via provider webhooks where available; otherwise a robust fallback)
• Built-in suppression lists and unsubscribe handling that work even when the sender is external
• Throttling/IP warmup tools (or at least provider-specific sending recommendations)
• Clear accountability: what your platform controls (templates, segmentation, automation, tracking) vs. what the sender controls (reputation, inbox placement, rate limits)

Net: marketers will accept BYO SMTP in the right niche and with great UX, but for the broader email marketing market, “we also provide sending” is often part of what they’re paying for—because it reduces deliverability and operational burden. If you share who your ideal customer is (SMB marketers, ecommerce, agencies, SaaS product teams, etc.) and the volumes you expect, I can tell you whether BYO SMTP fits that segment and what features matter most.