But aren't your other sites all using port 25?
But the point being that port 25 doesn't need authentication or SSL, 465 and 587 do, so unless you can enter those settings those ports won't work.
@licquorice: Thanks, my point exactly.
@mattcookeuk: If your monitoring site can't provide a SMTP on other than port 25 you won't be able to send emails from the DVR over the BT BB network.
I just wonder if you have sorted the email issue from your DVT yet as your post is quite old.
I have had the vary same problem and have been trying to fine a workround for over a year.
Yesterday I found the solution to my issue and hope it will shed some light on your issue.
I was setting up the smtp in the dvr using my BT ID which was not a BTInternet email but a gmail.
I went to the MyBT page and set up a new email address "firstname.lastname@example.org"
and hey presto the mail went straight through. So in order to get a DVR to send emails you must use a btinternet email address.
I hope this helps if you have not already sorted it