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POST
email.send

Authorizations

Authorization
string
header
required

A Lath API key: lath_live_sk… or lath_test_sk… on a server, lath_live_pk… or lath_test_pk… in a browser.

Headers

Idempotency-Key
string

Replays the stored response for the same key and input; refuses different input.

Body

application/json
to
string<email>
required

One recipient

Pattern: ^(?!\.)(?!.*\.\.)([A-Za-z0-9_'+\-\.]*)[A-Za-z0-9_+-]@([A-Za-z0-9][A-Za-z0-9\-]*\.)+[A-Za-z]{2,}$
template
string

A template name; provide variables with it

Required string length: 1 - 120
locale
string

Send the template's variant for this language, falling back to the broader language and then the default. Omit to use the recipient's own locale if one is recorded.

Maximum string length: 20
variables
object
subject
string

Inline send: the subject (with template, overrides the template's subject)

Required string length: 1 - 998
html
string

Inline send: the HTML body

Maximum string length: 200000
text
string

Inline send: the plain-text body; derived from html when omitted

Maximum string length: 100000
layout
enum<string>
default:brand

Inline send only: wrap the HTML in the project's themed frame

Available options:
brand,
none
from
string<email>

The project's default sender (omit) or any address on one of its verified domains

Pattern: ^(?!\.)(?!.*\.\.)([A-Za-z0-9_'+\-\.]*)[A-Za-z0-9_+-]@([A-Za-z0-9][A-Za-z0-9\-]*\.)+[A-Za-z]{2,}$
replyTo
string<email>
Pattern: ^(?!\.)(?!.*\.\.)([A-Za-z0-9_'+\-\.]*)[A-Za-z0-9_+-]@([A-Za-z0-9][A-Za-z0-9\-]*\.)+[A-Za-z]{2,}$
fromName
string

The name shown in the inbox beside the address. Defaults to the project's name; pass an empty string to send the bare address.

Maximum string length: 120
sendAfter
string<date-time>

Hold the message until this moment; omit to send now. Until it is sent it can be stopped with email.message.cancel.

Pattern: ^(?:(?:\d\d[2468][048]|\d\d[13579][26]|\d\d0[48]|[02468][048]00|[13579][26]00)-02-29|\d{4}-(?:(?:0[13578]|1[02])-(?:0[1-9]|[12]\d|3[01])|(?:0[469]|11)-(?:0[1-9]|[12]\d|30)|(?:02)-(?:0[1-9]|1\d|2[0-8])))T(?:(?:[01]\d|2[0-3]):[0-5]\d:[0-5]\d(?:\.\d+)?(?:Z|([+-](?:[01]\d|2[0-3]):[0-5]\d)))$
metadata
object

Up to 20 key/values echoed on every webhook about this message

attachments
object[]

Files to attach. Base64 content, at most 10 MB across all of them.

Maximum array length: 10

Response

{ activityId, result }. activityId is empty for reads.

activityId
string
required

The activity this call created, or empty for a read.

result
object
required
Last modified on September 13, 2026