In this guide · 8 sections
- 01What an MX record does, and why changes are risky
- 02Before you start: the preparation checklist
- 03The safe order of steps to change MX records
- 04MX values for Google Workspace and Microsoft 365
- 05What happens to email in flight during the change
- 06Common MX mistakes and how to spot them
- 07Do it yourself or get help?
- 08Frequently asked questions
Short answer
Lower the MX record's TTL to 300 seconds a day or two before, create every mailbox at the new provider, then replace the old MX record with the new one at a quiet time. Keep the old mailboxes active for at least a week and check both until no new mail arrives at the old one.
What an MX record does, and why changes are risky
An MX (mail exchanger) record is a DNS entry that says which server accepts email for your domain. When someone emails you, their server looks up your MX record and delivers to whatever it points at.
Two things make changes risky. First, DNS answers are cached for as long as the record's TTL (time to live) says, so for a while some senders still see the old MX. Second, if the new provider is not ready, it may reject mail for addresses it does not know. Both are avoidable.
| Term | Meaning | Typical value |
|---|---|---|
| MX record | Where your domain's incoming mail is delivered | smtp.google.com, or the value Microsoft 365 shows for your domain |
| Priority | Order to try when there are several MX records; lower number is tried first | 0, 1, 5 or 10 |
| TTL | How long other servers may cache the record, in seconds | 300 (5 min) to 86,400 (1 day) |
| DNS host | Where your DNS records are edited; may differ from your registrar | Registrar, Cloudflare, web host |
Before you start: the preparation checklist
Most MX problems come from skipping preparation. Do these a few days before the switch.
MX change preparation
If your website's DNS is in the same zone, be careful not to delete A or CNAME records while editing; our guide to connecting a domain without breaking email covers the reverse problem. If you are not sure who controls DNS, find out from your domain registrar first.
The safe order of steps to change MX records
This sequence works for any provider change. Allow two to three days from step 1 to the switch.
Lower the MX TTL at least a day ahead
Edit the current MX record and set its TTL to 300 seconds (5 minutes). Wait at least as long as the old TTL, often 1 hour to 1 day, so caches pick up the short value.
Get the new provider ready
Verify the domain, create all mailboxes and aliases, and start copying old mail. Do not change MX yet.
Pick a quiet time
Friday evening or a weekend morning works for most offices. Avoid month-end invoicing days.
Replace the MX record
Add the new provider's MX record exactly as shown, then delete the old MX records. Microsoft says to remove MX records for the previous provider or give them a lower priority than the new one.
Update SPF and add DKIM
Change the SPF TXT record to include the new provider and remove the old one if it no longer sends. Turn on DKIM at the new provider.
Check from outside
Use an online MX lookup or the provider's checker to confirm the new record is visible. Send test emails from Gmail, Outlook.com and a phone.
Watch both mailboxes for a week
Some mail still arrives at the old server while caches expire and senders retry. Check it daily, move anything new, then close it.
Raise the TTL again
Once everything is stable, set the MX TTL back to 3,600 seconds or your provider's default.
MX values for Google Workspace and Microsoft 365
Always copy the value from your provider's admin console, because some values are specific to your domain.
Google Workspace
- Single MX record: smtp.google.com, priority 1
- Older set-ups use several aspmx records, which Google still supports
- Google says changes can take up to 72 hours to be recognised
- Activate Gmail in the Admin console after adding the record
Best for: See Google's MX set-up article.
Microsoft 365
- MX value is shown on the Add DNS records page in the admin centre
- Priority set to the highest available, typically 0
- Microsoft lists TTL 3600 and says Exchange Online supports TTLs under 6 hours
- Add the autodiscover CNAME so Outlook finds the mailbox
Best for: See Microsoft's DNS records guide.
If your DNS is on Cloudflare, MX records are never proxied. Cloudflare's TTL documentation says DNS-only records can use a TTL from 60 seconds on non-Enterprise plans, and Auto means 300 seconds.
What happens to email in flight during the change
During the changeover window, a sender may still have the old MX cached. Its email goes to the old server. If the old mailbox still exists, the message is delivered there; if it was already closed, the message may bounce or be held.
Email is more forgiving than websites. The SMTP standard, RFC 5321, says a sending server that fails to deliver should retry, usually at intervals of at least 30 minutes, and generally keep trying for at least 4 to 5 days before giving up. A short outage usually means delay, not loss.
Common MX mistakes and how to spot them
If mail stops after a change, check these first.
- Editing the wrong DNS host: the registrar shows records, but the domain's nameservers point elsewhere, so changes do nothing.
- Old and new MX records both left in place with the same priority, so mail is split between providers.
- Typo or missing trailing dot in the MX value; some DNS hosts need one and some add it automatically.
- Mailbox not created at the new provider, so its mail bounces with user unknown.
- SPF not updated, so outgoing mail fails checks and lands in spam. See our SPF, DKIM and DMARC guide.
- Old service cancelled too early, losing mail sent during the changeover.
For a full mailbox move, including copying years of old email, follow our email migration guide.
Do it yourself or get help?
If you have DNS access and a handful of mailboxes, you can follow the steps above in an evening, as long as you prepared the mailboxes first. It gets harder with shared mailboxes, many aliases, a website that sends mail, or DNS spread across several companies.
Our Domain & DNS Setup service (S$99, paid upfront) handles the MX, SPF, DKIM and DMARC changes and checks propagation. If you also need old email moved, Email Migration (S$390) covers mailboxes, cut-over and the follow-up week.
Frequently asked questions
It depends on the TTL of the old record. If you lowered it to 300 seconds a day earlier, most senders see the new record within minutes. With a long TTL it can take hours. Google says new MX records can take up to 72 hours to be recognised everywhere, so keep the old mailbox open meanwhile.
Not if you follow a safe order. Create all mailboxes at the new provider first, keep the old mailboxes running for at least a week, and check both. Sending servers retry failed deliveries for days under the SMTP standard, so a brief problem usually delays mail rather than losing it.
Yes, once the new record is added. Leaving old MX records with the same or a better priority splits mail between providers. Microsoft's guidance is to remove MX records for the previous provider, or set them to a lower priority than the Microsoft 365 record. Lower numbers mean higher priority.
Use a short TTL, such as 300 seconds, for a day or two around a change so updates spread quickly. Afterwards, 3,600 seconds (1 hour) is a common setting, and it is the value Microsoft lists for Microsoft 365. Very long TTLs make future changes slower.
Usually yes. MX controls incoming mail, while SPF lists the servers allowed to send for your domain. When you move to a new provider, add its SPF include, remove the old provider if it no longer sends, and turn on DKIM. Otherwise your outgoing mail may fail checks and land in spam.