A mailbox on your own domain needs two things working together: the mailbox service itself, and the DNS records that tell the world where to deliver mail and whether to trust what you send. MX - where mail is delivered An MX record says which server accepts mail for your domain. Point it at your mail provider and messages arrive. A domain can normally have only one set of MX records pointing at one service at a time, so when you move providers, remove the old records rather than adding the new ones alongside. Changing MX affects delivery immediately. Do it when traffic is low, and have the new values ready before you start. SPF - who may send as you An SPF record is a TXT record listing the servers allowed to send mail for your domain. If the server you send through is not in the list, your own mail starts landing in spam folders. Keep it to one SPF record. Several records with the same name confuse receivers, and the result is unpredictable. DKIM - proving the message is yours DKIM adds a cryptographic signature to outgoing mail. Your provider gives you a TXT record to publish; once it is in place, receivers can verify that the message was not altered and came from a domain that authorised it. DMARC - what to do about failures A DMARC record tells receivers what to do with mail that fails SPF or DKIM, and where to send reports. Start with a monitoring policy so you can see what legitimate mail would be affected before you tighten it. Setting up a client Mail clients connect over IMAP to read and SMTP to send. The server names, ports and encryption settings are listed on the mail setup guide. The most common cause of cannot send is a wrong SMTP server, or a password that is not the mailbox password. Troubleshooting order Not receiving anything: check the MX record, then send a test from an outside mailbox. Receiving but not sending: check SMTP settings, then SPF. Your own mail going to spam: check SPF and DKIM, then DMARC. One device works and another does not: it is almost always that device server name or port setting.