I have been struggling with this issue for a few days now, and can't, for the life of me, figure out what the problem is.
I have created a SharePoint 2013 workflow which fires when an item is added to the Document Requests list. This workflow is to assign a task to me to approve the Document Request. If I approve, it is to send an email to the creator of the Document Request to tell them that the request is approved; if not, it is to send an email stating that it's been rejected. Please see this link showing the workflow steps: ![workflow steps]https://ibb.co/n6wfqv
What I have been struggling to understand is why it is not sending out the email to the task creator, or at least appears not to. It has sent out this email during one initial test, but stopped since.
The workflow completes without issue, and there aren't any errors/anomalies appearing in the ULS logs. I have tried adding a pause after the sending of the email to the request creator, as I have noticed that there is a delay of ~3 minutes between the creation of the initial Document Request and the approver task email, but to no avail.
I have not set up the SMTP server feature on the SharePoint server as we are pointing to a separate mail server, and, according to my knowledge, would not need this feature.
I assume that the issue would be with SharePoint/Workflow Manager not being able to communicate with this mail server, because the approver task email would not be sent out as well - is this a safe assumption?
Would the issue lie with the workflow, or with the Mail Server/Outgoing email configuration settings in Central Admin?
If there is another thread that answers this question, please point me in its direction. I have looked around, but could not find anything with a similar issue (frustration/lack of experience might be clouding my thoughts as well.)
Thanks for all your help :)