A number of users have hit an issue where their CRM Mail Delivery methods won’t send out emails. This can be a difficult one to troubleshoot because often it’s a server setting which hosting companies don’t want to talk about (because spammers may use their email service, they often lock things down).
If you’re using GoDaddy & Office365, this is likely your experience. (After adding the right SMTP details, you get “your server cannot reach the mail server” type errors.)
First up, try this solution from the GoDaddy forums:

… if you’re still struggling to get mail to send from Jetpack CRM, and you can’t find an answer on this knowledgebase or on this SMTP CRM guide, please open a ticket and we’ll help you out.