> ## Documentation Index
> Fetch the complete documentation index at: https://docs.ton.org/llms.txt
> Use this file to discover all available pages before exploring further.

<AgentInstructions>

## Submitting Feedback

If you encounter incorrect, outdated, or confusing documentation on this page, submit feedback:

POST https://docs.ton.org/feedback

```json
{
  "path": "/foundations/messages/external-out",
  "feedback": "Description of the issue"
}
```

Only submit feedback when you have something specific and actionable to report.

</AgentInstructions>

# Outbound external messages

Outbound external messages are the messages that a contract can send to the outer world. They are primarily used for logging purposes. They can't change any contract state or trigger a transaction. These messages are visible to anyone, and there is no guarantee that anyone outside the blockchain will process them.

The structure is as follows:

```tlb theme={"theme":{"light":"github-light-default","dark":"dark-plus"},"languages":{"custom":["/resources/grammars/tolk.tmLanguage.json","/resources/grammars/tlb.tmLanguage.json","/resources/grammars/fift.tmLanguage.json","/resources/grammars/tasm.tmLanguage.json","/resources/grammars/func.tmLanguage.json"]}}
ext_out_msg_info$11
    src:MsgAddressInt
    dest:MsgAddressExt
    created_lt:uint64
    created_at:uint32
= CommonMsgInfo;

message$_
    {X:Type}
    info:CommonMsgInfo
    init:(Maybe (Either StateInit ^StateInit))
    body:(Either X ^X)
= Message X;
```

Unlike [incoming](/foundations/messages/external-in) external messages, a third party can't manipulate the contents of outgoing external messages, so there is no need to sign them.

* `src` — an [internal address](/foundations/addresses/overview#internal-addresses) of the contract that sends the message. It has to be a valid address, but is not important, as it will be overwritten by the address of sender after the message is sent.
* `dest` — any valid [external address](/foundations/addresses/overview#external-addresses).
* `created_at` — arbitrary value, overwritten with the `created_at` field of the transaction in which the contract sent this message.
* `created_lt` — arbitrary value, overwritten with the `created_lt` field of the transaction, incremented by one.

When sending this kind of message, the contract may fill all of these fields with any values. `src`, `created_lt`, and `created_at` will be overwritten by the validator processing this message.

For an outbound external message, `init` field also can store arbitrary data, as outbound external messages can't initialize any contract.

## Message modes

As outbound external messages do not carry any Toncoin value, the price of their handling is paid similarly to [`SendPayFwdFeesSeparately`](/foundations/messages/modes) mode. However, using any mode other than [`SendIgnoreErrors`](/foundations/messages/modes), [`SendBounceIfActionFail`](/foundations/messages/modes), or [`SendPayFwdFeesSeparately`](/foundations/messages/modes) for outbound external messages results in [exit code `34`](/tvm/exit-codes#34:-invalid-or-unsupported-action). In this case, regardless of whether the [`SendIgnoreErrors`](/foundations/messages/modes) mode was used, the action phase will fail. Mode [`SendPayFwdFeesSeparately`](/foundations/messages/modes) does not change the message behavior.

## Example in Tolk

In Tolk, outbound external messages may be composed using the `createExternalLogMessage` function.

```tolk title="Tolk" theme={"theme":{"light":"github-light-default","dark":"dark-plus"},"languages":{"custom":["/resources/grammars/tolk.tmLanguage.json","/resources/grammars/tlb.tmLanguage.json","/resources/grammars/fift.tmLanguage.json","/resources/grammars/tasm.tmLanguage.json","/resources/grammars/func.tmLanguage.json"]}}
tolk 1.2

struct(0x10) ValueWasDeposited {
    value: int64
}

fun main(in: InMessage) {
    val msg = createExternalLogMessage({
        dest: createAddressNone(),
        body: ValueWasDeposited {
            value: 1000,
        },
    });
    msg.send(SEND_MODE_PAY_FEES_SEPARATELY);
}
```