Limits
The size, count, time and plan limits Mail enforces, read from the code that enforces them.
reference~3 minVerified v0.216.0
Plan limits are in Plans and limits: mailboxes, sends a month and a day, how long mail is kept, custom domains, gate modes and attachment size. This page holds the rest.
A message you send
| Limit | Value |
|---|---|
Recipients in to | 1 to 20 |
Recipients in to and cc together | 20 |
| Subject | 1 to 998 characters |
| Text | 1 to 100,000 characters, plain text |
| Note on a forward | Up to 20,000 characters |
idempotency_key | 1 to 200 characters |
An attachment larger than the plan allows is refused with attachment_cap. Mail sends no attachments from an agent: share an artifact of the workspace with the artifact argument of mail_reply.
What an agent reads
| Limit | Value |
|---|---|
Threads from mail_inbox | 1 to 50, default 20 |
Results from mail_search | 1 to 50, default 20 |
| Search query | 2 to 200 characters once trimmed |
Text of one message in mail_thread | 20,000 characters, then truncated is true |
| Allow list | 200 entries a mailbox |
HTTP API
| Limit | Value |
|---|---|
| Request body | 512 KB |
| Custom domain name | 4 to 253 characters |
Webhooks
| Limit | Value |
|---|---|
| Address | https, port 443, a public host name |
| Delivery timeout | 5 seconds |
| Retries | Up to 5 |
| Signature tolerance | 5 minutes |
A 3xx or 4xx answer other than 408 or 429 is final and not retried. See Webhook events.
Time
| Limit | Value |
|---|---|
| Time to undo an approved send | 5 seconds |
| Approve or decline link from the email | Works once, expires after 72 hours |
| Device code | 10 minutes, polled every 5 seconds |
Custom domains
| Limit | Value |
|---|---|
| Domains waiting for DNS at once | 2 |
| Domains added in 24 hours | 5 |
| An unverified domain with no mailboxes | Removed after 72 hours |
See Custom domains.
Inbound mail
A message larger than 25 MiB is not accepted. A message that scores 0.5 or more on injection screening is held back from the agent until a person releases it. See Screened mail.