When are custom thresholds worth it for Subject line is the approved one?
When are custom thresholds warranted?
Configuring this check is what switches it on, so the values are always yours. Set `approvedSubjects` for sends that went through review, and reach for `requiredSubjectPhrases` when an obligation attaches to wording rather than to the whole line — a promotional disclosure, a programme identifier, an advertising label. `prohibitedSubjectPatterns` is the right tool for wording your brand or legal team has ruled out, and `requiredSubjectPattern` suits structured subjects such as a mandatory prefix or ticket reference.
When should you stay on Standard?
There is no meaningful Standard state to stay on, because the unconfigured default is a skip rather than a verdict. The real decision is whether to include the check at all: if your subjects are not formally approved, leave it out rather than pasting in a list you will not maintain. For the common case of wanting to know whether the subject will survive the inbox, the length check is the one you want.
What do you trade away?
An exact approved-subject list is the strictest form and the most maintenance-hungry: every legitimate late edit becomes a failure until the list is updated, and a team that updates the list to make the check pass has inverted the control. Phrase and pattern rules are more durable but blunter, and a pattern written under pressure will eventually fail a correct subject in a way nobody can quickly explain. Prohibited patterns carry the usual over-reach risk, since a short prohibited string matches inside ordinary words.
Community Standard vs org Custom
Everything here is your organisation's own policy — there is no community default for what your subject line must say — so ownership matters more than usual. The approved list should come from wherever campaign sign-off is recorded, and required or prohibited wording from legal or brand, with each rule traceable to the obligation behind it. Because the output can serve as evidence that an approved subject actually shipped, keep a record of when the list was last reconciled with the review process.
Worked override examples
A regulated sender sets `approvedSubjects` to the exact lines legal signed off, so any post-approval edit fails before the send completes. An advertiser required to label promotional mail sets `requiredSubjectPhrases` to that label instead of an exact-subject list, keeping copy freedom while enforcing the obligation. A team gating AI-generated sends sets `requiredSubjectPattern` to the structure its templates must follow and `prohibitedSubjectPatterns` to the superlatives its brand guide bans, catching plausible-looking rewrites deterministically.
How does an agent call it with parameters?
{
"type": "email",
"validations": [
{
"id": "email-subject-content",
"parameters": {
"approvedSubjects": [],
"requiredSubjectPhrases": [],
"prohibitedSubjectPatterns": [],
"requiredSubjectPattern": ""
}
}
]
}