Bulk email - don't wat to get blacklisted as spam. SEO question?

[Nina May]

Hello all

We have a database of 80,000 customers, of which about 15,000 are regular users.

Following a website rebrand we would like to inform all of our customers there is no change to their login details and remind them of their unique account number.

Each email is to be personalised with name and account number.

Our server can send these out and we would be happy to send small chunks of emails over a period of days to avoid being labelled as a spam server, can anyone please advise a number that would be acceptable per day to email, or would shipping the whole list out in an excel document to a data broadcast compant be the safer option?

Your thoughts are very much welcomed
Thank you
Nina