I implore you to find one host that you can get on a virtual account with several dozens of other user's, or a VPS, or even a dedicated server someone else had used before & after the course of 1 day to 6 month's you don't get blocked by Barracuda networks.
I've had comcast/time warner & verizon e-mails blocked by IP via Barracuda Networks Anti-Spam firewall, that consisted of nothing but TEXT (no links) to friends & co-workers. They have the worst "fail-safe" over-blocking system in the world. You almost have to login to the control panel & add just your "known contacts" to ensure receiving a typical e-mail behind that hardware.
We successfully notify our dating site members every single day, thousands of e-mails per day, with no issue's in boxing at any ISP & we have our D.S. located in Webair's NYC DC. Once our site built up "trust" with e-mail providers, & removing all "sexual related" words & replacing them with innuendo's... we even got into the super strict ISP's behind tyrannical govt's backbone firewall's!
