How do I re-engage 50,000 lapsed SaaS subscribers without hurting email deliverability?

Hi! The safest way to re-engage a 50,000-person “old” SaaS list without tanking deliverability is to (1) make sure your authentication + unsubscribe compliance is rock-solid, then (2) ramp volume slowly starting only with the people most likely to recognize you, and (3) treat non-responders as “do not mail” rather than forcing 4–5 follow-ups to everyone. In practice, a “permission-pass” (reconfirmation-style) campaign to a small, high-likelihood segment first works better than blasting the whole database or immediately emailing 50k multiple times in a month.

Here’s a playbook that works well for lapsed subscribers.

1) Fix the “table stakes” first (before you warm anything)

If any of these are off, you’ll see exactly what you described: things look OK in tiny batches, then fall apart once you scale.

• Use a reputable ESP for marketing mail (not a DIY SMTP) unless you have deep deliverability ops. ESPs handle IP reputation, feedback loops, bounce handling, TLS, queueing, etc.
• Separate your streams/domains:
  • Keep transactional mail (password resets, receipts) on its own sending setup/domain so marketing issues can’t harm critical mail.
  • Consider sending reactivation from a subdomain (e.g., notifications/updates subdomain) while keeping your core brand domain consistent in the visible “From” name.
• Authentication: ensure SPF + DKIM + DMARC are set up correctly and aligned with your From domain (DMARC passing is especially important at higher volumes).
• One-click unsubscribe + fast honoring: add proper List-Unsubscribe headers (including one-click) and make unsubscribing painless. This reduces “mark as spam,” which is the #1 killer during reactivation.
• List hygiene basics: remove obvious bad addresses before sending (previous hard bounces, known complainers, role accounts like support@/admin@ if they’ve historically performed poorly, etc.).

2) Don’t “warm up” on the full list—warm up on the most likely openers

With a lapsed list, your biggest risk isn’t just reputation—it’s near-zero engagement + spam complaints. So you want your first waves to generate opens/clicks.

Segment aggressively, for example:

1. Most recent activity (last login, last purchase, last support ticket, last meaningful product event)
2. Most recent email engagement (if you have it), even if it’s old
3. Paid > free (paid users are more likely to recognize you)
4. Source/intent (people who requested demos or trials tend to remember you more than “downloaded a freebie” folks)

Start with the smallest “best” segment first, and only expand when metrics are healthy.

3) A practical ramp plan (safe and simple)

You don’t need a perfect schedule, but you do need controlled scaling.

• Day 1–3: send to your best segment only (often a few hundred to a couple thousand).
• Then scale gradually (think “step up,” not “10x overnight”), watching:
  • complaint rate (people clicking “spam”)
  • hard bounce rate
  • open/click trends (direction matters more than any single number)
• If metrics dip: pause expansion, resend only to recent openers/clickers, and tighten targeting.

Tip: If you have a mixed mailbox-provider list, you can also ramp by provider (Gmail/Yahoo/Microsoft can behave differently), but segmentation by “likelihood to recognize you” is usually the bigger win.

4) Reconfirmation: yes—but do it the right way

A “please confirm you still want this” email can work, but sending it to everyone at once is still a big deliverability gamble.

What tends to work best:

• Permission-pass email #1 goes only to your best segment first.
• Anyone who clicks (or completes a preference action) becomes your “confirmed re-engagement” audience for follow-ups.
• Anyone who does nothing should be suppressed after 1–2 attempts, not chased 4–5 times.

Also, avoid anything that looks like a deliverability trick (e.g., “reply to this email to stay subscribed”)—keep it clean: one clear CTA to manage preferences or opt back in.

5) How to run 4–5 follow-ups in a month without damaging deliverability

You can do 4–5 touches—but not to the entire lapsed file. Do it to a shrinking, engagement-based segment.

A solid approach:

• Email 1 (to best segment): “We’re back—do you still want updates?” + preference options + clear value.
• Email 2 (only to openers/clickers): what’s new + one primary CTA.
• Email 3 (only to clickers or high-intent): a focused offer (extended trial, migration help, concierge setup).
• Email 4 (same engaged segment): social proof/case study + FAQ.
• Email 5 (last call, still only engaged): “Keep hearing from us?” + preference center.

Meanwhile, non-openers/non-clickers get at most 1–2 total reactivation attempts, then you stop. That “stop mailing the silent majority” move is what protects long-term sender reputation.

6) Quick diagnosis of what likely happened to you

Given “deliverability dropped sharply once I sent beyond a small batch, and engagement was close to zero,” the most common causes are:

• the list is old enough that many addresses are abandoned/recycled (hurts reputation fast)
• low recognition → low opens + higher spam complaints
• missing/misaligned DMARC/DKIM/SPF and/or missing one-click unsubscribe headers
• sending too much too fast on a domain/IP with limited recent history

If you tell me (a) roughly how long it’s been since you last emailed them (6 months? 2 years?), (b) whether you have any recent in-app activity data, and (c) which From domain you’re using for marketing vs transactional, I can suggest a tighter segmentation + ramp plan that fits your situation.