Transactional email for my own website

[alento]

@kurucu

So using (e.g. Mailgun) to send e-mail with the appropriate DNS records is enough? Is the separation the mg.domain.com and box.domain.com sufficient to allow both to send @domain.com e-mails without running into spam problems?

Provided that you configure your SPF and DMARC records correctly, yes.

@kurucu

I found the other place that throws me off. Go to admin / Mail & Aliases / Instructions and see:

Use only this box to send as you

Your box sets strict email sending policies for your domain names to make it harder for spam and other fraudulent mail to claim to be you. Only this machine is authorized to send email on behalf of your domain names. If you use any other service to send email as you, it will likely get spam filtered by recipients.

Perhaps wording that needs tweaking in a future update.

The only wording change would be adding what I wrote above, but most users do not have the need to tweak their settings. Yours is an exceptional use case.