I have a firebase application with some Node.JS functions running on Firebase Cloud Functions.
One of these functions is sending a mail using nodemailer. Whenever I use a gmail account in my SMTP connection, everything is working fine. However, now I want to use my custom domain e-mail to be the sending all the e-mails.
Whenever I verify the SMTP connection with my custom domain e-mail, using nodemailer's verification code, it seems all is working fine. But then no mails are actually being sent.
My domain provider told me I probably need to add an IP or some kind of general SPF Record to my domain to allow this to happen. They linked me to an article where an example is given with Mandrill. In that example I believe they just use the Mandrill service as the "external app" that is allowed in the custom domain.
Now in my case there is no Mandrill in between, just a nodemailer function running in the cloud. How would I go around setting up SPF records for something like this? I'm really not familiar with DNS and this might be a rilly silly question, but any help in the right direction is really appreciated!