Some mails are not sent

Hi,
I have a big problem on the site of a customer: approximately 15% of the emails are not sent. I use three different forms on this website, this error occurs on all and I can't find any rules of this error. But all entries are stored in the database.
The customer is naturally upset because this error cost him money.
Any ideas?
Thanks in advance
Martin

I have found a rule: it affects all emails from gmx.de, hotmail.com and .de, googlemail and some from web.de. All other sender addresses work.

Hi Martin,

How do you know? It's pretty unlikely; in my experience if ChronoForms sends one email then it sends them all. If some aren't delivered they are mostly likely to be in the client's spam folder.

Bob

Hi Bob,
thank you for your quick response!
I have set up a test-mail address where all emails of the 3 forms are sent in copy. When I compare the entrys of the database with the received emails, I can find the lost emails.
I just tried it with my own gmx-adress: the data is written into the database, but there is no email sent. Or no email has arrived. The spamfolder is empty.
Martin

Next step: in one of the forms I use now a static mailadress from the sender. Now it works. But I need the address of the customer as sender.

Hi Martin,

Please use the Reply To Name and Email address boxes to do this.

Bob