[Exim] port 25 blocking

My internet provider has blocked port 25 so I can no longer send
email from my own computer but have to go through their smtp
account.

Is there anyway around this port 25 block? I understand that
all computers listen on port 25 as the default mail port, so if I
sent mail from another port it would not be received on the
other end , is that correct?

As an alternative is there a way to set exim up to forward my mail
through their smtp port using my username and password without
it being stopped as spam by their servers?

Stinking spammers, they have screwed things up for everyone.

Thanks for any help.

Larry