Hello Guy,

Will log a ticket internally to get our designers to take a look at.

Okay Mark, let me know when you've some news.

FYI, You should know whitelisting your domain will only help from my servers and local email clients. It is not a complete solution.
You are blacklisted on multiple lists and those emails go to dev/nul disappearing to outer space before they ever would reach my servers or email box.

The blacklists are maintained by third parties all of which have their own set of rules and conditions for having you removed. In some cases it can take days or even weeks. To bout, there are many "Private" blacklist you'd never know your on. For example AOL amongst others have a "private/secret" lists you could be on protecting their customers from spammers. AOL customers wouldn't see anything in their personal spam box as AOL have already intercepted.
You see once you're on multiple blacklists you're pretty much screwed. It can take a lot of time and manual work to repair the damage.

Cheers! /Guy

Having a dedicated IP from Sendgrid is a little costly as these are just transactional e-mails, I am still speaking with them right now.

Mark,
If you didn't know this already, be aware forking out for a dedicated IP will not only cost more but is still no guarantee you'll not end up on blacklists anyway. This is because webmasters / webhosts tend to take a whole group of IP numbers around the allegedly offending spammers IP and block them all.
I know there's collateral damage. Fair or not, that's what happens.

The best method is to start at the top. Double check you've continually fresh updated opt in opt out email lists. Run your advertising emails through software for spam before they are sent.
You'd be surprised to see what you think is perfectly okay and defiantly not spam, is not what others might think.
Get yourself on some whitelist that are available out there and keep an eye on the blacklists. There are many automated options to choose from.

Good luck with this Mark.

Cheers! /Guy

Noted, thanks for your insights on this Have you tried any transactional email providers out there?

Can't say I have,
Acymailing and MailChimp > http://mandrill.com/ are the ones I personally use. It's not a recommendation, simply the ones I've used for years especially the first mentioned Acymailing.

Although this link is a little old it's still got useful info. https://blog.mailchimp.com/what-is-transactional-email/

Cheers!

Hm, we previously used Mandrill too but it had the same issues. Switched over to SES and hit the same issue. Now, we switched over to Sendgrid and also hitting similar issues

Need to find a reputable transactional email provider :x