Hey David,
Thanks for reaching out. Please try the following.
- Go to Settings->General
- If blank add 1.1.1.1 as primary and 8.8.8.8 as secondary DNS
- Save
- Try to enable DKIM.
- If there are already DNS servers entered in please remove the entries.
- Save
- add 1.1.1.1 as primary and 8.8.8.8 as secondary DNS
- Save
- Try to enable DKIM.
Let me know if this helps.
Thanks,
Zach Sylvester
Software Developer
SmarterTools Inc.
www.smartertools.com