How do I validate email addresses in a LangChain agent?

Steps

1. Install langchain-strale and a chat-model package.
2. Create the toolkit with your Strale API key.
3. Bind email-validate to your model.
4. Ask about an address and run the tool call the model returns.

The solution

# pip install langchain-strale langchain-openai
from langchain_strale import StraleToolkit
from langchain_openai import ChatOpenAI

toolkit = StraleToolkit(api_key="sk_live_YOUR_KEY")
tools = [t for t in toolkit.get_tools() if t.name == "email-validate"]

llm = ChatOpenAI(model="gpt-4o").bind_tools(tools)
result = llm.invoke("Is user@example.com a valid, deliverable email address?")

# The model picks the tool and its arguments; your code runs the call.
for call in result.tool_calls:
    tool = next(t for t in tools if t.name == call["name"])
    print(tool.invoke(call["args"]))

How it works

The check covers the syntax (format_valid), the DNS (has_mx_records: does the domain accept mail?) and some signals about the address: is_disposable for throwaway providers, is_role_address for addresses such as info@ or support@, and is_free_provider for providers such as Gmail.

valid is the overall answer. There is no single deliverability score, and the separate flags let your agent apply its own policy, for example rejecting disposable addresses and flagging role addresses for review.

A valid result does not prove that the mailbox exists, and new disposable domains can be missed.

bind_tools only lets the model propose a call. To have the model read the result and answer in words, put the same tools in one of LangChain's agent loops.

Tools in this guide