premier installed allowing gmail but blocking my website server emails?

I have done the certificate thing recommended in fixes but to no avail. I have mail coming through Thunderbird on windows 8 64bit. gmail is coming through ok and I can send on it but the email linked through my website are no longer coming thru. All settings appear to be ok…Help…anyone else out there know of this and a fix please.

We are going to need some more information. Is it a corporate email server or commercial e-mail like gmail via thunderbird?

If it is gmail via thunderbird, is it using IMAP or POP3? Did it work before you installed Premier?