# Suspicious Sender

*Reputation*. An email sender who sends email messages to recipients that never granted explicit permission to that sender.

Some suspicious activity could be unintentional. If a [trusted sender][trusted] send either an excessive amount of email or who send at an alarming frequency, recipients might flag their messages as [spam][]. An recipient ISP might [throttle] the sender's email messages, send them to [spam traps], or [block][] the emails outright.

> \[!WARNING]
>
> You might encounter the term *black hat sender*. The term *suspicious sender* replaces that term and eliminates any potential racial or cultural connotations associated with the earlier term.

## Related entries

* [Bulk email folder][]
* [Domain authentication][]
* [Email deliverability][]
* [Email harvesting][]
* [Sender authentication][]
* [Suspicious Sender][]
* [Trusted Sender][trusted]

## Related resources

[Email deliverability tips](/docs/sendgrid/ui/sending-email/deliverability/)

[trusted]: /docs/sendgrid/glossary/trusted-sender

[spam]: /docs/sendgrid/glossary/spam

[throttle]: /docs/sendgrid/glossary/throttling

[spam traps]: /docs/sendgrid/glossary/spam-traps

[block]: /docs/sendgrid/glossary/blocks

[Email harvesting]: /docs/sendgrid/glossary/email-harvesting

[Suspicious sender]: /docs/sendgrid/glossary/suspicious-sender

[Bulk email folder]: /docs/sendgrid/glossary/bulk-mail-folder

[Email deliverability]: /docs/sendgrid/glossary/deliverability

[Sender authentication]: /docs/sendgrid/glossary/sender-authentication

[Domain authentication]: /docs/sendgrid/glossary/domain-authentication