Skip to content
Browse docs · DNS & authentication

MX records - why senders still need them

Updated Apr 6, 2026 · 4 min read

MX is for inbound, but cold senders without MX get penalised anyway.

On this page · 2
  1. Why senders need MX
  2. The Inboxlee default

MX records tell the world where to deliver mail addressed to your domain. For a sender-only domain, operators sometimes skip MX entirely. That is a mistake.

Why senders need MX

Bounces, auto-replies, and DMARC reports all return to the From address. Without MX, those messages disappear. You lose the bounce signal that warmup tools rely on, the unsubscribe-loop reply path, and the DMARC report stream.

Worse, missing MX is itself a deliverability signal. Mailbox providers see a domain with SPF and DKIM but no MX as a one-way blast cannon. They notice.

The Inboxlee default

Every domain we provision ships with the full Google Workspace MX stack - five records, correct priorities, no manual editing:

1   ASPMX.L.GOOGLE.COM
5   ALT1.ASPMX.L.GOOGLE.COM
5   ALT2.ASPMX.L.GOOGLE.COM
10  ALT3.ASPMX.L.GOOGLE.COM
10  ALT4.ASPMX.L.GOOGLE.COM

The mailbox is real, replies route to a real inbox, and bounces return cleanly. This is non-negotiable for a credible sending domain.