Hubspot does allow you to purchase a dedicated IP so that you are not sharing your IP with anyone with their service. But as far as integrations go, Hubspot simply allows companies to integrate with their platform and it is up to those vendors to provide support. In the case of Mailgun they don't appear to have developed a native integration with Hubspot. Per their website the integration must be done with Zapier ( https://www.mailgun.com/resources/integrations/hubspot/ ).
Hubspot does allow you to purchase a dedicated IP so that you are not sharing your IP with anyone with their service. But as far as integrations go, Hubspot simply allows companies to integrate with their platform and it is up to those vendors to provide support. In the case of Mailgun they don't appear to have developed a native integration with Hubspot. Per their website the integration must be done with Zapier ( https://www.mailgun.com/resources/integrations/hubspot/ ).
