I am trying to test a mail out before sending. When I send test to my personal email address, it says sent but doesn't arrive. When I send test to a company email address it says sent but doesn't arrive. When I send to a gmail address, it says sent and DOES arrive! Any ideas what might be the problem? I'm on a deadline! Thanks
In addition to JonG's answer, I would definitely recommend using a professional SMTP Gateway. For instance we pay 10€ / month for 10 000 emails with great deliverability. They will provide SPF and DKIM entries for your Domain and your emails will reach their recipients. In CiviCRM you just need to set the parameters and you're done!
There is likely one of two things wrong, but both will need a technical administrator to resolve. This answer will necessarily be technical; I'm sorry if that's not immediately helpful. The good news is that assuming one of these is true, it will only affect users at your organization.
Most likely, you're on G Suite or other hosted mail service, and your SPF record doesn't include your CiviCRM SMTP host. You will need to know what your CiviCRM SMTP host is (check Administer menu > System Settings > Outgoing Email). If your setting is "mail" or "sendmail", the server is the same as the one CiviCRM is hosted on. Make sure it's in your SPF record (or create an SPF record if you don't have one). G Suite and other hosted mail providers block mail that appears to be within the organization otherwise because it's a common tactic of spammers.
The other possibility is that Mail is being relayed to a misconfigured SMTP server. I've seen this with Postfix - in
/etc/postfix/main.cf, check your
mydestinations setting and ensure your organization's domain name isn't listed there.