I have always been attracted to the Subscribe-to-Comments plugin, but at the same time installing it has always filled me with dread. Whilst it can be a great community building aid, and a useful tool for regular visitors who like to interact, it can be a liability.

There are 2 aspects of subscribe to comments that present a danger to a successful business blog

• Email Flow Control
• Legal compliance with CAN SPAM and SI (3429 of 2006)

Email Flow Control

By default, the wp_mail() function of WordPress uses PHPs mail() function, a way of sending instant emails from your server. Unfortunately, most popular hosts have restrictions on how many emails can be sent from your server over 24hrs, and it is very typical for there to be an hourly limit as well.
As an example, here are the Hostgator policy for email delivery:-

There is a 200 hourly email limit per domain this limit is also applied towards mailman. If you send over this amount in any hour most of the e-mails will bounce back with a undeliverable error.

They also suggest one email every 6 seconds – unfortunately if 50 people have subscribed to comments, one new comment sends 50 emails out, which in my opinion is quite worrying.

Most hosts have PHPMailer installed, or available for installation, and you could try your luck using wpPHPmailer plugin, though this seems to be unsupported these days (1 year+ and no reply from developer in the support thread) – support for PHPMailer has actually just been added to WPMU. PHPmailer itself hasn’t been updated in a long time, thus I am slightly hesitant to use it, though I am not technical enough to give a reason for my pessimistic stance.

Swift Mailer & the ShiftThis SMTP Mailer Plugin are the alternative that we are going to use instead, and both are actively supported.

ShiftThis SMTP Mailer Plugin

Installing this plugin is actually extremely easy, as long as you don’t disappear off in the wrong direction. The plugin comes with Swift Mailer already in a sub-folder.
You don’t need to visit the Swift Mailer site at all. If you are not extremely technical, you could waste hours, if not days digging around the Swift Mailer site, and then the the various testing applications. None of that is needed.

Installation:

Download plugin
Extract plugin
Copy / Upload to your normal plugin folder

Configuration:

You could set it up to use your local SMTP server – that would then however count towards how many emails you are sending from your domain, which might not be an ideal situation.

You could also set things up to use Gmail – I can actually think of all kinds of benefits to using Gmail for your SMTP, though if a site is a company site, you might want to use one of the upgraded Google offerings. Also take a look at this old Lifehacker article. You will also have to decide whether you really want your sent email within Gmail to fill up with comments being posted to your blog.

Currently the code doesn’t seem to support the email flow control plugin of Swift Mailer, but if you are using Gmail for SMTP this might not be a problem. I have submitted a message on the support forums to see if this can be integrated with some easy to understand flow controls.

Legal compliance with CAN SPAM and SI (3429 of 2006)

I should note:-

• I am not a lawyer, and the wording I have used was not written by a lawyer
• You should check with your legal consultant and this is provided for entertainment purposes only

No matter how effective your spam controls and how restrictive your comments policy, commercial email messages can get through, and a subscribed email recipient could just as easily claim “this is spam” for a comment subscription as they would for a mailing list.

It is quite common for people engaged in internet marketing to use an email service such as Get Response or Aweber to ensure delivery of their emails, and to protect against spam complaints.

This solution isn’t necessarily going to help with email delivery, but at least offer some “cover your a$$” protection should you happen to receive a complaint.

Whilst elsewhere I have been challenged to provide conclusive proof that you should take precautions with any aspect of your email usage, I am not going to offer that in this write up.
You may well look on this as scare tactics and FUD.

It is your choice based on your own research and the legal advice you have received whether you think emails being sent from your domain which are not totally under your control could represent a problem.
I honestly don’t know if Safe Harbour rules might apply to email delivery. I don’t know of any blog owner who has had problems either from a legal perspective, or with their hosting or domain registrars, but then I personally only know a few people who have been killed in car accidents – I know a lot more people who drive cars than publish business blogs.

Subscribe To Comments Hack

This is just a hack. I decided to offer a hack for those concerned and don’t intend to offer a patched file. Ideally Subscribe To Comments should offer an interface in the options to allow various additional messages to be added to outgoing email messages. This wouldn’t necessarily just have to be legal information, it could also include additional advertising.

Around line 600 I have added the following:-

[PHP]
$message .= __(“\n\nWarning: Emails generated from comment subscriptions may contain commercial messages. Whilst every attempt has been taken to eliminate comment spam, the content should not be regarded as approved by the blog owner\n”, ‘subscribe-to-comments’);
$message .= __(“Keedz Ltd – Registered in England & Wales: 05906883\n”, ‘subscribe-to-comments’);
$message .= __(“Registered Address: 71 Bexley High St, Bexley, Kent DA5 1AA +48(62)7382438\n”, ‘subscribe-to-comments’);
[/PHP]

Conclusion

As stated this is all for entertainment purposes.

If you are concerned with emails being sent out from your blog, and how they are controlled, making these changes might take you anywhere from 1 to 2 hours. Once you get the hang of it, making the changes on multiple blogs will take just a few minutes, especially if you create a hacked version of the plugin that is suitable for all your web properties.

My own personal belief is it is worth dotting the legal “i”s, and crossing the “t”s if you are serious about your online business. I still have a few I need to handle.

Maybe one day the email mailing list services will offer a host of additional services for bloggers, including adding commenters to mailing lists and providing a safe, monitored email gateway.