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Email in Flex limitations


Not a HIPAA Eligible Service

Email in Twilio Flex is not a HIPAA Eligible Service and should not be used in workflows that are subject to HIPAA.


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Once the Twilio account is linked with a SendGrid account, you cannot unlink it yourself. If you need to change, unlink, or delete the linked SendGrid account, contact our support team(link takes you to an external page) for help.

Please discuss TaskRouter scalability with your Twilio team, particularly for managing a backlog of tasks. The maximum number of Tasks in TaskRouter is 25,000.

The following file types are supported for attachments: .pdf, .jpg and .jpeg, .png, .gif, .mp3, .mp4, .txt, .heic, and .amr. Other file types are not supported as attachments at this time.

Inline attachments--an attached file, such as an image, that appears the body of an email--are currently supported for inbound emails only. For outbound emails, agents must use the paperclip icon to select and add their attachments.

Email size (inbound, including attachments)20MB
Email size (outbound, including attachments)20MB

Out-of-order processing of inbound emails is possible. For example, if an end user sends multiple messages in quick succession, Twilio may process the second message before the first. This limitation is complex and impacted by the implementation of mailbox providers. Additionally, unwanted emails coming from spam senders or a malicious actor may impede the processing of valid emails.

Following are the scalability limitations for Email in Flex:

Create a new email interaction20 requests per second
Accept email reservations20 requests per second
Add new participants to email conversation20 requests per second
Remove participants from email conversation20 requests per second

Email in Flex uses the Conversations API and its associated limits.

Actions (e.g., new email conversations and new email messages)30 actions per second
Inbound email processing25 inbound emails per second (subject to change based upon the number of attachments)

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