How to warm up a domain

Marketers change sending domains for a variety of reasons, including:

  • A brand change
  • A corporate restructuring
  • A change in the location of a data center

Domain reputation is increasingly used by mailbox providers to identify spam, so ensuring that they are introduced to a new domain properly is vital to reducing the likelihood of deliverability problems. Although the email industry has no specific guidelines for warming up a domain, you should take a conservative approach and treat a domain warm-up similar to an IP address warm-up.

What to expect

  • You may encounter some deliverability problems, especially in the first week, while the new domain is building a sending reputation.
  • Some mailbox providers may place some of your email in the spam or junk folder to see if subscribers rescue it and label it as not spam.
  • On average, building a sending reputation on a new domain takes about 30 days. It may take longer depending on:
    • The volume of email being sent
    • The quality of the subscriber list
    • How frequently you send email

Domains for daily senders generally warm up faster than those for weekly senders.

  • If  the warm-up is rushed or mismanaged, deliverability problems will likely occur.
  • AOL and Gmail are more likely to need a longer warm-up period.

Pre-warmup checklist

Before warming up the domain:

  • Create a Sender Policy Framework (SPF) record for the new Return-Path domain (if applicable). For domains that will not be used to send email, create an empty SPF record (v=spf1 -all).
  • If you are changing the DomainKeys Identified Mail (DKIM) domain, create a new DKIM domain (d=) and sign up that domain with the Yahoo! feedback loop. 
  • Update IP-based complaint feedback loop addresses if the old domain is deactivated and was used to receive feedback loop messages.
  • Create a Domain-based Message Authentication, Reporting, and Conformance (DMARC) record and set the policy to monitor (p=none). For domains that will not be used to send email, set the policy to reject (p=reject).
  • Update the WHOIS record for the domain with correct information and do not use a domain privacy service.
  • Set up a mail exchange (MX) record for the new domain to allow for incoming email.
  • Create the abuse@ and postmaster@ role accounts and add them to
  • Ensure all complaint feedback loops work properly and that complainers are added to a suppression list.
  • Ensure the bounce-handling process works properly, especially if the Return-Path domain has changed.
  • Determine if you need to notify subscribers about the change. Some subscribers will have your old sending address in their address book, so it may be necessary to send an email notifying them of the change and encouraging them to add your new sending address to their address book.

Best practices and warm-up guidelines

  • Start with a low sending volume (a maximum of 5,000 subscribers per mailbox provider, per new domain, per day). If you cannot target specific mailbox providers, start with a volume of 5,000 total subscribers.
  • Target active subscribers in the beginning, since positive engagement helps build trust in the new domain with mailbox providers.
  • Double the sending volume every three to four days until you reach your maximum daily volume.
  • Pause the warm-up if results do not meet expectations. Warming up a new domain is not an exact science, so it is important to monitor performance, pause the warm-up, and troubleshoot if problems occur.
  • Monitor performance using:
    • Internal performance tracking systems or those of your mailbox provider
    • Inbox Monitor
  • Phase in the change over time to build your new domain's sending reputation. On average, a warm-up may take 30 days to build a sending reputation with a mailbox provider, but it may go faster or take longer depending on your sending practices and sending reputation.  

The warm-up process will go more smoothly if you use IP addresses with good sending reputations and that are signed up with Return Path's Certified whitelist, since trust in the IP address helps establish trust in the new domain. If you already have a poor sending reputation and do not follow email marketing best practices, it is likely deliverability problems will continue, regardless of the domain change.

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