Mailscale shared IP risks are no joke. Learned this the hard way
gregemailops · 2026-02-17 · 2,340 views
I was on mailscale.io for about 3 months. Everything was going fine until one day my deliverability tanked overnight. Reply rates crashed to near zero.
After investigating, I found out another user on the same shared IP was sending spam. Their bad behavior affected everyone on that IP including me. I had zero control over it.
This is the fundamental problem with shared SMTP infrastructure for cold email. Your deliverability depends on every other sender on your shared IP. One bad actor can tank your entire operation overnight.
Switched to PuzzleInbox Google Workspace inboxes. Each inbox sends through Google's infrastructure with my own authenticated domain. No shared IP risk. My deliverability recovered within a week. Lesson learned: never share email infrastructure with unknown senders.
Comments (4)
outboundowen · 2026-02-17
shared IP is basically rolling the dice every day. one bad neighbor and you're toast. been there done that
inboxwhisper · 2026-02-18
This is exactly why dedicated Google Workspace inboxes are worth the extra cost. You send through Google's infrastructure with your own authenticated domain. No shared IP risk at all. The deliverability difference is night and day.
bouncebetty · 2026-02-18
how did you figure out it was a shared IP issue? was there a specific tool or did you just eliminate everything else?
gregemailops · 2026-02-19
@bouncebetty I checked MXToolbox for blacklists and found the IP was listed on Spamhaus. Then I contacted Mailscale support and they confirmed another user on the same IP had been sending at extremely high volume. That's when I knew I needed dedicated infrastructure.