# Sending emails with Letta using [Resend](https://resend.com/emails)
Thank you to @ykhli for the suggestion and initial tool call code!
## Defining the custom tool
Create an account on [Resend](https://resend.com/emails) to get an API key.
Once you have an API key, you can set up a custom tool using the `requests` API in Python to call the Resend API:
```python
import requests
import json
RESEND_API_KEY = "YOUR_RESEND_API_KEY"
RESEND_TARGET_EMAIL_ADDRESS = "YOUR_EMAIL_ADDRESS"
def send_email(self, description: str):
"""
Sends an email to a predefined user. The email contains a message, which is defined by the description parameter.
Args:
description (str): Email contents. All unicode (including emojis) are supported.
Returns:
None
Example:
>>> send_email("hello")
# Output: None. This will send an email to the you are talking to with the message "hello".
"""
url = "https://api.resend.com/emails"
headers = {"Authorization": f"Bearer {RESEND_API_KEY}", "Content-Type": "application/json"}
data = {
"from": "onboarding@resend.dev",
"to": RESEND_TARGET_EMAIL_ADDRESS,
"subject": "Letta message:",
"html": f"{description}",
}
try:
response = requests.post(url, headers=headers, data=json.dumps(data))
print(response.text)
except requests.HTTPError as e:
raise Exception(f"send_email failed with an HTTP error: {str(e)}")
except Exception as e:
raise Exception(f"send_email failed with an error: {str(e)}")
```
## Option 1 (dev portal)
To create the tool in the dev portal, simply navigate to the tool creator tab, create a new tool called `send_email`, and copy-paste the above code into the code block area and press "Create Tool".
Once you've created the tool, create a new agent and make sure to select `send_email` as an enabled tool.
Now your agent should be able to call the `send_email` function when needed:
## Option 2 (CLI)
Copy the custom function into the functions directory:
```sh
# If you use the *_env_vars version of the function, you will need to define `RESEND_API_KEY` and `RESEND_TARGET_EMAIL_ADDRESS` in your environment variables
cp examples/resend_example/resend_send_email_env_vars.py ~/.letta/functions/
```
Create a preset that has access to that function:
```sh
letta add preset -f examples/resend_example/resend_preset.yaml --name resend_preset
```
Make sure we set the env vars:
```sh
export RESEND_API_KEY=re_YOUR_RESEND_KEY
export RESEND_TARGET_EMAIL_ADDRESS="YOUR_EMAIL@gmail.com"
```
Create an agent with that preset (disable `--stream` if you're not using a streaming-compatible backend):
```sh
letta run --preset resend_preset --persona sam_pov --human cs_phd --stream
```
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