This recipient looks invalid: this message appears when the recipient is globally bounced.

To unblock this address from receiving emails, you'll need to provide proof that the contact is legitimate and wants to receive emails. This error also may appear if an email address is a known spam trap.

The recipient requested to not receive any emails via HubSpot: this message appears when an individual recipient reported an email from HubSpot as spam or has explicitly requested to not receive emails from any HubSpot accounts.

This company has opted out of all email types: this message appears when the company has explicitly requested to not receive emails from any HubSpot accounts.

This 'from' address looks invalid: this message appears when the sender's email address fails our validation attempts due to a syntax error.

The email address in the 'to' field failed validation: this message appears when the recipient's email address fails HubSpot's validation attempts due to a syntax error.

The recipient previously unsubscribed from all subscription types: this message appears when the recipient has previously unsubscribed from all your email subscription types.

The recipient previously unsubscribed from this subscription type : this message appears when the recipient has opted out of that email type.

A previous email to the recipient was flagged as spam: this message appears when an email to the recipient has previously been marked as spam.

This recipient looks invalid - previous sends to this address have bounced: this message appears when an email to the recipient has previously bounced.

You may see Not sent emails for sales or marketing emails and additional messaging depending on the Not sent reason. The system will only block emails from sending if there's a high probability that the email will not be delivered or if it would be illegal to send an email to that particular contact. HubSpot uses Not sent emails to preserve your sending reputation.

This message displays on a contact record when an email was not sent to the contact. A Not sent email is different from an email bounce. In these cases t he email is never sent from HubSpot, so the email can't bounce.

To be sent or to be send