Best practices for sending transactional email

Sending transactional email is a great way to establish and maintain communication with your customers. However, sometimes transactional email is filtered into the spam folder or blocked by a mailbox provider. It is frustrating when this happens since most transactional email is sent to a subscriber based on an interaction they had with your company such as a product purchase or password reset request.

An important insight about mailbox providers to understand is that they look at your IP address and domain sending reputation to determine filtering decisions regardless if the email is transactional or promotional. So if you have a poor IP address or domain sending reputation, it will likely lead to filtered or blocked email.

As with all email, following best practices helps improve your chances of reaching the inbox. Follow these troubleshooting tips should deliverability problems occur.

Common types of transactional email

  • Receipts, order confirmations, shipping confirmations, password resets, legal notifications, policy updates, registration confirmation, abandoned shopping cart, and re-engagement.

Potential causes for transactional email spam folder placement

  • Causes of transactional email spam folder placement vary and often relates to a lack of proper disclosure and setting the right expectations with the subscriber about the content and frequency of the email they will receive.
  • Transactional email is sometimes affected by bulk marketing email when sent using the same IP address or domain. If the marketing email stream or campaign is encountering excessive complaints or hitting spam traps, then a mailbox provider may start placing all email, including transactional email, into the spam folder as a precaution.
  • Transactional email may be sent containing text only, non-branded email templates, which look like spam. If a subscriber doesn’t recognize the sender, they often mark the email as spam.

Transactional email best practices


  • Send transactional email from a separate IP address and domain space than your bulk marketing email. Marketing email can affect the filtering of transactional email since marketing mail often has a lower engagement rate and may not always adhere to sending best practices.
  • Sign up for all complaint feedback loops to monitor complaint rates for your transactional mail. Even though you don’t suppress or unsubscribe subscribers from all types of transactional mail, complaint feedback can help troubleshoot causes of filtering or blocks.

Tracking and monitoring:

  • Monitor the deliverability of your transactional email stream. Send transactional messages to Inbox Monitor deliverability at different times throughout the day and send the transactional messages at the same time marketing email is sent. Should deliverability problems occur, it will help determine if there are specific patterns relating to the day, time of day or relation to other email streams that may be contributing to filtering or blocks.
  • Monitor unsubscribe requests and remind subscribers that it is a transactional message. Give them an option to unsubscribe from all marketing emails.

Execution and disclosure:

  • Don’t automatically opt-in a subscriber for marketing emails. Subscribers may perceive all future messages to be spam, including transactional messages.
  • Clearly outline to the subscriber that they will receive the transactional messages and how to recognize them.
  • Remind subscribers when they can expect to receive the transactional message. This applies more to notifications and updates.
  • Send transactional messages in timely manner. Even a delay of an hour from when the action took place to when the email is sent may cause some subscribers to perceive the message as spam.
  • Suppress or unsubscribe subscribers from non-essential transactional messages such as abandoned shopping cart messages.
  • If sending a large volume of transactional messages (like for a product release update) at one time, spread them out over a period of several days to a week. Mailbox providers are sensitive to sudden and unexpected increases in volume so spreading out the send can help reduce deliverability problems.


  • Use a relevant subject line that specifically describes the type of content for the transactional message.
  • Write relevant information in the pre-header to help the subscriber understand the content of the message. Don’t just repeat the subject line.
  • Use a recognizable friendly-from or display name.
  • Keep the transactional messages branded to match the marketing email in order to increase recognition.
  • Make the transactional messages easily read on mobile devices by using responsive design techniques.
  • Include value added content to some transactional messages such as a list of other items that were purchased or links to helpful videos. If subscribers perceive added value to your messages, they may be more likely to engage with the message which can improve inbox placement.
  • Review the appearance of all transactional messages in Inbox Preview to ensure the message is free from HTML or design errors.
  • Allow subscribers to reply to email. People don’t normally reply to spam messages, so subscribers replying to your email add to a positive sending reputation. Upon receiving a reply, either respond directly from a customer service representative or send an auto response email with instructions on how to contact customer service.
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