How do I prevent my shipment is classified as SPAM?

[Gazaway_w]

I run a website and I will have to make weekly shipments of mail, however, after the first mails, they are almost every time classified SPAM.

It's very, very annoying as it is developing the site.

The base is 33,000 emails for each shipment.

My question is how to prevent my shipment is considered as SPAM?

Thank you.

[Aikonik]

Hi.

Unfortunately there is no magic bullet to this problem. Sometimes the mail will be classified as spam and sometimes it will not.
But to put all chances on your side up and avoid the mails do not fall into the spam, you must specify the headers (headers), you can read this to help you.

[robodude]

If you still sending your mails to the same people, tell them you "despammer. In all cases, doing now to prevent your mail that your recipients may be considered as spam

[johnson22]

After if you mail server administrator, you can install some programs that can prove to the servers (yahoo, hotmail) that does not send you spam

[checkmate]

I have heard of SPF field and everything :-)

Could you guide me through these steps?

I am the admin of the mail server