Tangentially, I've been using my own domain with Gmail for years, but as of ~1y ago, it's been causing me problems. Emails sent from such custom addresses to my domain (which forwards back to my gmail) get a "This might be phishing" banner.
See, Gmail lets you configure it so that you can send emails as another address. This required a bit of verification via a DNS check, but trivial if you controlled your domain.
However, with the advent of SPF/DKIM/DMARC enforcing, this doesn't work well anymore. My main problem is that my domain is configured to forward select emails back to gmail. This breaks SPF, and I haven't yet found a way to fix this with Gmail.
I guess I need to wade through some SPF/DKIM/DMARC documentation. Google's own has not been useful.
Here are the records I am using with cloudflare. Ive never had an issue
@
v=spf1 a mx include:_spf.google.com include:_spf.mx.cloudflare.net ~all
_dmarc
v=DMARC1; p=none; rua=mailto:my@emai.com; aspf=r;
The way I have it set up is that cloudflare catches all my email and then routes it to my gmail account. My gmail then uses my email as a "send as" address. No DKIM record is needed because google is the one sending the emails with smtp, but dmarc and spf are needed either way.
The way to do this forwarding would be to remail it in the same way that mailing lists do, rather than a SMTP forward.
The sender (SMTP envelope sender) gets rewritten, and so SPF is good. The From: header stays the same. SPF doesn't care about the From: header, only the SMTP envelope sender.
See, Gmail lets you configure it so that you can send emails as another address. This required a bit of verification via a DNS check, but trivial if you controlled your domain.
However, with the advent of SPF/DKIM/DMARC enforcing, this doesn't work well anymore. My main problem is that my domain is configured to forward select emails back to gmail. This breaks SPF, and I haven't yet found a way to fix this with Gmail.
I guess I need to wade through some SPF/DKIM/DMARC documentation. Google's own has not been useful.