Email subscription

As the guides its nice to send thread updates to email subscribed members every day or week and they selelcted in User CP. I am using Google Apps for my domain and free edition only allows 500 and premium only 2000 mails per day from an account. So If we have lot of members we can't use apps for subscription mails.
1. We can use sendmail in php will they get as junk bcoz our mx records pointing google?
How to set spf records or domain keys for this issue?

2. News letter sending companies are extremely expensive for this daily job, so is it possible to setup a VPS and send mail from SMTP of it? Or is it possible to use sendmail fuction of some other VPS for this?

I noticed now vbulletin contact us page mails end up in gmail spam folder and telling about phishing. Because vbulletin makes contact us emails appear as coming from the senders email, but actually sending from your own servers php send mail.
Anyone noticed that?

Hello,

All of this is core functionality within vb and is not related to vbseo. You should consult their support for more information on their mailing functionality.