I do not receive any more mails
If you use a mail program such as Outlook and you find that you can no longer send mail then you should first check your incoming server. This should be imap.mijnhostingpartner.nl or pop.mijnhostingpartner.nl. If you are still using pop.JeDomeinNaam.nl then you need to further modify this.
Have you adjusted this but you still receive no mails then you need to further check the MX records in your control panel. To do this you first need to be logged in and click on domains.
Then click on the domain that is giving you problems.
Then click on edit dns zone records.