Should transactional and marketing emails be sent from separate domains or subdomains?

Email marketer from Medium says, "Never, ever send transactional emails from your marketing domain."

Email marketer from Litmus shares using subdomains gives you more control over reputation management, and enables you to more easily segment your traffic.

Email marketer from Quora explains separating transactional email assists with knowing how many orders/requests are being made.

Email marketer from Sendinblue explains that separating transactional and marketing emails allows you to isolate reputation damage. If your marketing emails have deliverability problems, your transactional emails can continue unimpeded.

Email marketer from Reddit explains using a root domain can result in deliverability issues if the reputation becomes damaged.

Email marketer from WebHostingTalk shares that keeping your transactional emails apart is a great way to ensure they're delivered quickly. Important notifications like password resets, welcome emails, or receipts are better served if separated from your marketing campaigns.

Email marketer from SparkPost shares that segmenting email traffic by type and sending it from different subdomains (or even domains) protects your sender reputation and improves overall deliverability.

Email marketer from Mailjet shares that it’s a best practice to separate transactional and marketing emails to protect your sender reputation, allowing you to quickly identify the root cause of any deliverability issues and address it immediately.

Email marketer from ActiveCampaign responds that using separate subdomains for different types of email communications helps you avoid deliverability issues, as problems with one type of email won't affect the deliverability of others.

Email marketer from StackOverflow shares how separating the emails assists with bulk email deliverability.

Expert from Email Geeks explains that if a base domain is used for employee email addresses, it may be better to move marketing and transactional emails to their own subdomains to keep non-1:1 email separate.

Expert from Email Geeks shares that changing the From: address may cause you to lose any customer-specific whitelisting you may have had, however, if your mail is generally welcomed it shouldn’t be a problem.

Expert from Word to the Wise explains that separating email streams is generally a good idea for reputation management and deliverability, and specifically recommends doing so for marketing and transactional emails.

Documentation from Amazon Web Services recommends using separate, dedicated IP addresses for transactional and marketing emails to maintain deliverability and track performance independently.

Documentation from MxToolbox answers separating marketing and transactional emails enables you to better test for email deliverability issues.

Documentation from Google Workspace Admin Help explains that sending marketing and transactional emails from separate IP addresses or domains can help maintain a good reputation for each type of email.

Documentation from RFC shares the need to separate different types of email is important for sender ID and authentication purposes.