我可以从不同的服务器使用PHP检索POP3邮件吗?

I tried to retrieve my POP3 E-Mail with PHP from a different server which is out of E-Mail server's domain, by referring to simple sample PHP codes for test.

But I have encountered some errors such as 'imap_open : couldn't open stream...', searched for answers, I found an answer that I need to check the user name and password, a server might block the E-Mail transfer, etc.

Because I have no experience on mail processing with PHP, I have doubt if I can access the E-Mail server from another server, where my PHP code is in.

Because my E-Mail server is a commercial one, I cannot upload my PHP file on the server.

Can I create a web E-Mail client to retrieve my mails from the E-Mail server?

I will be appreciated for any help of you, Thanks.