Do you notice communication with your customers ends up in the spam folder of the larger ISP’s like AOL and Yahoo.com?
We did recently. Customers complaint that they never received an web hosting invoice or domain renewal notice.
Some were mad because support did not reply to their issues.
Every time we receive such a complaint we look into our logs and ticket system and found that the e-mails went out just fine but obviously never arrived at the customer.
Some research and testing later we found that a large amount of e-mail was either blocked or put into the spam folder.
Now keep in mind that we pride ourselves to keep our mail servers clean, no spammers or even large bulkmailers are tolerated.
We even run a dedicated Mail Server just for HelpingHost.com customer communication but it did not help.

After some investigating we narrowed the Solution down to using an external SMTP Service that would manage the mail server reputation for us.
We found the following contenders:

• SendGrid
• JangoSMTP
• Socketlabs
• Postmarkapp

Luckily all three offered small free accounts so that we could test each one out.

JangoSMTP and PostMarkapp have the big advantage of a very fine grain step up in cost.
You almost only pay what the emails you send out and get the same features for any plan you are on.

With Socketlabs you also get (almost) all the features in every plan but the cost are much steeper and have some big gaps in between.

Sendgrid starts pretty cheap ($9.95 per month for 40000 emails) but you only get a subset of features with that cheap plan. Missing are Whitelist services, Feedback loops and such.
The next step up already $80 per month for 100.000 emails. A step in the middle would be nice.

After the first round of testing we were pretty much set on SocketLabs but during actual use we noticed a feature missing in SocketLabs that was provided by Sendgrid and that is and automatic insertion of a un-subscribe footer.
We are relying on some non-opensource software and so we can not simply add function and features such as a un-subscribe link to them. Sendgrid simply does this for us.

As you can see, each of these Services have a lot to offer and it really depends on what exactly you need to make a decision what is the best.

We ended up with Sendgrid for now and are enjoying a much more consistent communication with our customers. It also just feels much better if you KNOW your email will arrive at the recipients Inbox.

One last thing that is quite nice and provided by all four of the services are very detailed statistics about your email even down to if somebody opened the e-mail or clicked on a link within the email.