MX Records Guide
By Abdul Sami, GTM Engineer · 4 min read · Last updated
MX (Mail Exchanger) records tell the internet which servers accept email for your domain. Each record has a priority lower numbers are tried first. A domain with no MX records generally cannot receive email, and sending to addresses there hard bounces.
Reading an MX record
'10 aspmx.l.google.com' = priority 10, server aspmx.l.google.com. Senders try the lowest priority first and fall back in order. Multiple records at the same priority load-balance.
Common provider values
| Provider | Primary MX |
|---|---|
| Google Workspace | aspmx.l.google.com (+ 4 alternates) |
| Microsoft 365 | yourdomain.mail.protection.outlook.com |
| Zoho | mx.zoho.com |
| Proton | mail.protonmail.ch |
Migration mistakes
- Leaving old MX records after switching providers mail splits between two systems.
- Changing MX before mailboxes exist at the new provider mail bounces.
- Forgetting that MX changes propagate at TTL speed; lower TTLs the day before.
FAQ
- How do I check a domain's MX records?
- Use the MX Checker on this site, or any DNS lookup tool querying type MX for the domain.
- Can a domain have no MX record?
- Yes and it usually can't receive email (some senders fall back to A records, unreliably). For lead verification, no MX means undeliverable.
- Why do MX records matter for cold outreach?
- Checking MX on your lead domains removes the biggest hard-bounce source, protecting sender reputation. Checking your own ensures replies can actually arrive.
Abdul Sami
GTM Engineer, DFY GTM Systems
7+ years building outbound systems for B2B companies across the US, UK, Australia, and DACH. Specializes in Clay workflows, cold email infrastructure, intent-based lead sourcing, and deliverability.
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