Forum updated to NodeBB v1.13.0
Please open a topic in the support area if you notice any new issues.
I also realised I hadn't made an spf record for our domain and some email notifications to Gmail had failed on occasions (due to number of subscribers on Gmail). Should be sorted now.
(Triggered when sending similar emails to many Gmail accounts at once and Gmail thinking it was spam). If we still get issues, I can look into other authentication methods they recommend.