To ensure your email is safe, why not just get a Hotmail or Google account? OK it's a one-off change but will remain no matter who your ISP is.I have never regretted it.
Due to price and caps I moved from Zen, who were excellent, to Plusnet. This is for BB only and I notice the difference, this may be just a local issue, they claim it is not contention ratio but I do not believe them.
You pays your money and take your chances for 12 months.