HubSpot

HubSpot's email-authentication article generates two DKIM CNAME records, an SPF TXT record, and a DMARC TXT record when you connect a marketing sending domain. HubSpot's troubleshoot article says the SPF record should include include:shared.hubspot.com.

The record

v=spf1 include:shared.hubspot.com ~all

HubSpot recommends a dedicated email subdomain rather than reusing the subdomain that hosts website content. If an SPF TXT record already exists for the sending domain, HubSpot's troubleshoot page says to append HubSpot's include to that same record instead of publishing a second SPF TXT.

Four record types

HubSpot's manage-authentication flow also lists MX for the connected sending domain as part of the connection checklist. Copy each host and value from HubSpot's domain settings into the DNS provider.

HubSpot's DMARC troubleshooting section says only one TXT record at _dmarc may start with v=DMARC1, matching RFC 7489's expectation that receivers discover a single policy record.

Merge SPF

HubSpot's troubleshoot article appends include:shared.hubspot.com to an existing SPF TXT instead of creating a second v=spf1 record.

HubSpot recommends an email subdomain that is not already used to host website or blog content.

Dedicated IP customers follow additional A, MX, and CNAME steps documented in HubSpot's knowledge base.

What is SPF
SPF is a TXT record that starts with v=spf1. It lists the hosts allowed to send mail for the domain. Two records that both start with v=spf1 on the same name are a permerror.
What is DKIM
DKIM signs a message. The public key is a TXT record under _domainkey. The signature's s= tag is the selector and d= is the signing domain.
Brevo
Brevo's domain authentication article lists the SPF and DKIM DNS records shown in the Brevo account after you add a sender domain. The exact TXT values are generated per domain in the control panel.