email marketing though email campaigns from Sugarcrm

Hi Experts

I am having sugar crm professional edition hosted in my network behind the firewall , one of our marketing activity is to keep executing the email campaigns , for this we did subscribe for the smtp service from one of the email service provider the reason is to avoid our smtp server black listed,

1.  now by using the third party smtp service for the email campaigns, messages from the crm server to the thrid party subscribed smtp server are going very much slow hence this is resulting in huge messages/mails in the CRM server Queue and time taken to reach the third party smtp server is more ( too much delay)

2.whatever messages found to be delivered it is in the spam , we observed this for gmail accounts , please note we have also added SPF records
New TXT record is :
v=spf1 a mx include:netcore.co.in ~all


please do the needful how to avoid messages landing to the spam also delay from sugarcrm sever to reach thridparty smpt server

thanks in advance