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

# mySMTP Deliverability Toolbox: Free Email Sender Tools

> Use the free mySMTP Deliverability Toolbox at toolbox.smtp.ai to check SPF, DKIM, DMARC, rDNS and MX, build BIMI records, plan IP warmup and clean lists.

No account is required and there are no rate limits. Every check runs in your browser, so your data is never sent to mySMTP servers.

<Card title="Open the Deliverability Toolbox" icon="toolbox" horizontal href="https://toolbox.smtp.ai/">
  19 free tools for DNS, authentication, deliverability and more
</Card>

## Tools by category

<Tabs>
  <Tab title="DNS & Authentication">
    | Tool | Use it to |
    | - | - |
    | **SPF Validator** | Expand every `include:`, count DNS lookups (limit 10), and catch syntax errors and weak `~all` / `?all` endings |
    | **DKIM Checker** | Verify a domain and selector, key type and key length (warns under 1024 bits) |
    | **DMARC Wizard** | Build a DMARC record step by step: policy, alignment, report addresses and percentage |
    | **One-Click SPF / DKIM / DMARC Checker** | Get a pass/warn/fail summary of all three, including alignment with your From domain |
  </Tab>

  <Tab title="Deliverability">
    | Tool | Use it to |
    | - | - |
    | **Warmup Plan Generator** | Get a day-by-day warmup schedule for a new IP or domain |
    | **Sender Readiness Checklist** | Run a pre-send check of authentication, rDNS, unsubscribe and list hygiene |
    | **Blacklist Checker** | Check your sending IP and domain against major blocklists, with delisting links |
    | **MailWizz Quota Optimizer** | Calculate batch sizes, delivery servers and schedule for MailWizz campaigns |
  </Tab>

  <Tab title="Branding & BIMI">
    | Tool | Use it to |
    | - | - |
    | **BIMI Generator** | Create the BIMI TXT record for `default._bimi.yourdomain.com` and preview your logo |
    | **BIMI SVG Converter** | Convert a standard SVG logo to the required SVG Tiny PS format |
  </Tab>

  <Tab title="Diagnostics">
    | Tool | Use it to |
    | - | - |
    | **MX Lookup** | List a domain's mail servers, priorities and IP addresses |
    | **PTR / rDNS Checker** | Confirm your sending IP has a matching reverse and forward DNS record (FCrDNS) |
    | **Bounce Code Decoder** | Turn SMTP responses such as `550 5.1.1` into a plain-English cause and fix |
    | **Email Header Analyzer** | Trace relay hops and delays and read SPF, DKIM and DMARC results |
    | **What Is My IP** | See your public IPv4/IPv6 address, PTR and ASN |
    | **CNAME Lookup** | Trace CNAME chains for tracking, bounce and DKIM domains |
  </Tab>

  <Tab title="Utilities">
    | Tool | Use it to |
    | - | - |
    | **Email List Analyzer** | Find syntax errors, duplicates, role and disposable addresses before you import a list |
    | **Email Template Verifier** | Check an HTML template for unsubscribe links, broken links and spam triggers |
    | **Password Generator** | Create strong SMTP passwords locally in your browser |
  </Tab>
</Tabs>

## Which tool to use when

| Situation | Start with |
| - | - |
| Setting up a new sending domain | [One-Click SPF / DKIM / DMARC Checker](https://toolbox.smtp.ai/), then the DMARC Wizard |
| Starting on a new dedicated IP | PTR / rDNS Checker, then the Warmup Plan Generator |
| Emails landing in spam | Sender Readiness Checklist and Email Header Analyzer |
| A message bounced | Bounce Code Decoder |
| Sending was suddenly blocked | Blacklist Checker |
| Before importing a new list | Email List Analyzer |

## Related guides

<CardGroup cols={2}>
  <Card title="SPF, DKIM, DMARC and BIMI" icon="key" href="/deliverability/spf-dkim-dmarc-and-bimi-explained">
    What each record does and how to publish it
  </Card>

  <Card title="Warm-up plans" icon="temperature-arrow-up" href="/deliverability/warm-up-plans">
    How to ramp up a new IP safely
  </Card>

  <Card title="Blacklists" icon="ban" href="/deliverability/blacklist-monitoring-and-delisting">
    Monitoring and delisting
  </Card>

  <Card title="Common SMTP errors" icon="triangle-exclamation" href="/troubleshooting/common-smtp-errors">
    Fix the most frequent sending errors
  </Card>
</CardGroup>


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