Have you looked at adding a .tpl.extra file? This can be a very easy way to add more content to any template.
Instructions are here.
One way to do that would be:
Create a drupal webform where you show the CiviCRM user and the Event and a Submit button that registrates the visitor to the Event.
If you use a checksum token in the link then the person you mail will be shown on that page.
CiviMail isn't responsible for anything other than Bulk Mailouts.
There are Scheduled Jobs required for things like Scheduled Reminders which you can find at civicrm/admin/job?reset=1
In case you hadn't spotted, there have been two SparkPost extensions released. the other is here. Not suggesting either is better, or even how relevant it is to your issue
Can you check if you have turned on send receipt? You can check by navigation to CiviCRM >> Contributions >> Manage Contribution Pages
Click on Configure link besides the contribution page and then 'Thankyou and receipting'
Once you on receipt page scroll down and check the box 'Email Receipt to Contributor?' if its turned off.
Also check under 'Profiles' ...
I've found the answer.
I was calling GroupContact > Create with parameter Status=Pending. This worked to create the pending contact but as far as I can find there is no way to then trigger the double opt-in email.
The solution is instead to call MailingEventSubscribe > Create, with parameters for email address and group id. This adds the pending ...
There was a problem with that: https://lab.civicrm.org/dev/core/issues/713 which was fixed by https://lab.civicrm.org/dev/core/issues/644 which is marked as fixed in 5.11 Upgrading should fix your issue.
If PDF processing is the issue, consider installing wkhtmltopdf. It's much more efficient than the built-in PDF generation.
It can't ship with CiviCRM because it's written in a compiled language - so unlike CiviCRM, which can run unmodified on Windows, Linux, MacOS, etc., wkhtmltopdf is OS-specific (and to some extent, processor-specific). However, it's ...
Although not a perfect solution, it turns out to be the PDF processing that is causing it to time out (known issue apparently).
I disabled the PDF generation for emails and everything works fine now.
Edit the Workflow Message for the event receipt template to include a ticket at the bottom. You can style it with html/css to look like you want. In order to have the ticket always be at the bottom of the page, you can use nested tables.
Here is a similar question (How) can I add a footer fixed to the page of a message template for printing a pdf?
Josh - By the look of the invoice, it seems the width isn't adjusted correctly in your pdf file. Civi normally assigns width statically to the table added in the message templates. So my first attempt would be to either remove the width attribute from the <table> element and test the pdf receipts OR modify the width in the table tag to some other value ...
I've often found good luck by switching to wkhtmltopdf. It's written in a coding language that makes it tough to distribute directly with CiviCRM, but takes a few minutes for someone who knows what they're doing to install. Someone posted wkhtmltopdf instructions here.
Not sure if this applies, but there is a known issue regarding receipts and payment recording for recurring payments.
PR-8615 corrects this and is scheduled to be merged into the 4.7.10 release, or you can apply it yourself to 4.7.6.
I've recently had to address this issue.
1) Make sure that the PayPal's "callback" setting is enabled and set to point to your website.
2) Speak with your sysadmin and make sure that calls from PayPal are not being blocked.
3) Look in your CiviCRM logs around the time of the payment to see if there are any errors.
4) Ask your friendly neighbourhood ...
You may have been here / tested already, but I believe if you are in Drupal Webform, there is another 'confirm subscription' configuration under the 'Additional Options' tab which is checked by default.
You probably saw this but there is a second setting that deals with Double Opt-In - but since you only referred to one, the other one is
Enable Double Opt-in for Profiles which use the "Add to Group" setting
When CiviMail is enabled and a profile uses the "Add to Group" setting, users who complete the profile form will receive a confirmation email. ...