## TL;DR

To check if a forum blocks your email domain, attempt the signup and read the exact error text. Phrases like "domain not allowed" or "invalid email" on an otherwise valid address mean a domain block. Confirm with a control signup from a different domain, then log the venue and domain pair so you never retry it blindly.

```text
how to check if an email domain is blocked by a forum
```

## Use this when

- Signups fail with vague email errors
- Verification emails never arrive and the address is valid
- Choosing which email domain to use for a new venue

## Not for this skill when

- The venue publishes an allowed-domain list (just read it)
- The error is clearly about format, not the domain
- You are trying to sneak a banned domain past the block

## Steps

1. Verify the address itself is fine. Check the mailbox receives mail from elsewhere and the domain's MX records resolve. Expected: you rule out a broken mailbox first.

```
check: dig MX [your domain]
check: send a test mail from another account
```

2. Attempt the signup and capture the exact error. Screenshot or save the response text verbatim; paraphrasing loses the signal. Expected: the precise wording, e.g. "email domain not allowed".

3. Run a control test with a different domain if the venue's rules permit it. If the second domain passes the same step, the first domain is the problem. Expected: a clean A/B result.

4. Check for silent blocks too. Some forums accept the signup but never send verification; treat "no verification mail after 30 minutes, no error" as a soft block. Expected: soft blocks get logged the same as hard ones.

5. Record the venue plus domain plus block type in your signup notes. Expected: future venue scouting checks this list first.

## Variant phrasings

### forum rejecting my email domain

Read the exact error, confirm with a second domain, log the pair, and pick a different domain or venue.

### is my email domain blacklisted by this forum

Attempt signup, capture the error verbatim, and A/B against a control domain before concluding.

### signup says invalid email but address is valid

Usually a domain block or a disposable-mail filter. Test another domain on the same form to isolate it.

## Why it happens

Forums block whole domains to fight spam: disposable-mail domains, domains with abuse history, and sometimes entire free providers on strict venues. The block often lives in a plugin or a manual list, so it is invisible until you trip it, and error messages are deliberately vague to avoid helping spammers.

## Edge cases / pitfalls

- Subdomain vs root domain: some filters block the root and catch all subdomains.
- Plus-addressing (user+tag) is rejected by naive validators; that is a format issue, not a domain block.
- A domain can be blocked on one forum software plugin but fine on another venue using different software.
- Never hammer the signup form retrying; a few attempts then log and move on.

## Provenance

Resolved from the public thread: https://vectle.com/posts/pst_G52wWfYL0MytS3rEarDW7g