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Email Limits and Guidelines
There are several ways to use Marketing Cloud Engagement to send email, including Email Studio, Journey Builder, SOAP API, and REST API. When you send email, there are limits that apply to throughput, file size, and data retention policies.
IP Address Limits
Two types of IP addresses can deliver email: shared IP addresses and dedicated IP addresses. Shared IP addresses are a pool of IP addresses that are used to deliver mail sent by several Marketing Cloud Engagement customers. Dedicated IP addresses are addresses that only a single customer can use, either in one account or across several accounts in the same stack.
Customers who send more than 250,000 messages per month must use dedicated IP addresses. This requirement prevents the actions of one sender from having an outsized impact on message delivery for messages sent using shared IP addresses. Using dedicated IP addresses helps high-volume senders control the reputations of their IP addresses, because they’re the only senders who can send email using those addresses.
| Resource | Maximum | Details |
|---|---|---|
| Maximum number of emails that can be sent using shared IP addresses | 250,000 emails per month | This limit is a guideline. Your sending rate isn’t throttled if you exceed this limit. If you plan to send more than 250,000 emails per month, contact your account executive to discuss obtaining a dedicated IP address. |
| Maximum number of emails that can be sent from a single IP address | 2 million emails per day, per IP address | This limit is a guideline for fully warmed-up IP addresses. Your sending rate isn’t throttled if you exceed this limit. Each new dedicated IP address must complete a warmup process. During the warmup period, a small volume of email traffic is sent using the IP address. The volume of email traffic sent through the dedicated IP address increases gradually over time. The warmup process takes 31 days to complete. |
| Maximum number of dedicated IP addresses per account | No limit | We recommend that you only obtain the number of dedicated IP addresses that you require for your use case. The reputation scores of IP addresses decrease over time if they aren’t used to send consistent volumes of email. |
Message Size and Length Limits
Email messages often include images and file attachments. You can include attachments in messages that you send using Email Studio and the API.
| Resource | Maximum | Details |
|---|---|---|
| Maximum attachment size | 5 MB | Only certain file types are supported. Email inbox providers can remove certain types of attachments (such as ZIP files) without notifying you. A large attachment can also cause a subscriber's inbox to reach its storage capacity, preventing you and other senders from reaching them with relevant messages. This limit applies to all sends, including messages sent via Reply Mail Management. |
Email Archive Limits
Email Studio includes the ability to archive email messages to align with regulations. Email archiving isn’t a long-term backup solution, and can reduce the speed at which you can deliver email messages.
| Resource | Maximum | Details |
|---|---|---|
| Maximum message retention period | 21 days | Archived messages only include the message body. Images and other attachments aren’t archived. |
Triggered Email Limits
A triggered email is a message that Marketing Cloud Engagement sends in response to an action, such as sending a confirmation message when a customer makes a purchase.
| Resource | Limit | Details |
|---|---|---|
| Expiration period for unsent messages | 3 days | Triggered send messages are marked as expired if they aren’t processed or sent within 3
days of being added to the sending queue. When the message sending system takes a request
from the queue, it compares the current time to the timestamp of the original request. If
the difference between timestamps is more than 3 days, the message isn’t sent and the
system logs an A common cause of expired messages occurs when you pause a triggered send and later resume it without clearing the sending queue. This expiration period helps prevent you from unintentionally sending messages that are out-of-date. |
