Issues sending some emails

Thanks again

So what you're suggesting I do reset my PTR record to beststylesusa.com. I can definitely ask my provider to do that.
Second: set the SPF record for beststylesusa.com and "v=spf1 mx ~all". I *thought* this was set already, so if you know how to do this I would appreciate it if you showed me.
Third: set my hostname in Linux to beststylesusa.com - THIS concerns me because although I know how to do it, I'm not sure ISPConfig will continue to function after I do this.

sERGE

 

Valid SPF records

Also, as a side note, I went to this site to see what I could find:

http://www.kitterman.com/spf/validate.html

I went to the DOMAIN NAME spot, entered my domain (beststylesusa.com) and got the following output:

SPF record lookup and validation for: beststylesusa.com

SPF records are published in DNS as TXT records.

The TXT records found for your domain are:
v=spf1 mx ~all

Checking to see if there is a valid SPF record.

Found v=spf1 record for beststylesusa.com:
v=spf1 mx ~all

evaluating...
SPF record passed validation test with pySPF (Python SPF library)!

It looks like I have a valid SPF record, so I am not sure why mxtoolbox is saying I don't . . .

sERGE

 

Yes, You must set PTR to be like that. You have SPF setup made with TXT record. There is second record type called SPF exactly. I have no idea how you must add it with Your domain provider. Different providers got different type of panels for that. I do not know Yours.
The Kitterman site show you got it, because you have it inside TXT. But You don't inside SPF record. Some older mail server may not read TXT correctly and try to search for SPF only.
ISPConfig will work with any hostname in Linux system. It is used by software in the system, not by ispconfig.