Switched from shared SMTP to Google Workspace. 8 week before after data

infra_convert · 2026-05-13 · 1,920 views

Ran cold email on shared SMTP (Mailforge) for 6 months. Switched to Google Workspace (PuzzleInbox) 8 weeks ago. Here is the before/after data.

Shared SMTP baseline (6 months).

Reply rate: 1.4% average. Bounce rate: 4.2%. Spam placement: 22%. Inbox placement: 65%.

Puzzle Inbox Google Workspace (8 weeks).

Reply rate: 4.2% average. Bounce rate: 0.9%. Spam placement: 3.1%. Inbox placement: 89%.

The infrastructure difference.

Reply rate 3x higher. Bounce rate 4.6x lower. Spam placement 7x lower. Inbox placement 24 points higher.

Same variables, different outcomes.

Same copy. Same ICP. Same sending platform (Instantly). Same volume (15 emails per inbox per day). Only variable changed was infrastructure from shared SMTP to real Google Workspace.

Cost impact.

SMTP was $0.80/inbox + $25/inbox warmup = $25.80/inbox/month. Puzzle Inbox pre-warmed GWS = $3-4.50/inbox with warmup included. Actually cheaper AND better deliverability.

What this validates.

The Google Workspace IP reputation inheritance effect is real and significant. Shared SMTP cannot match it at typical cold email volumes. Pre-warming included eliminates warmup tool costs. Dedicated vs shared infrastructure matters at every volume.

What I wish I had done earlier.

Switched 6 months sooner. Cost me roughly 200 meetings worth of pipeline to use shared SMTP during that period. Lesson learned.