feat(mail): allow setting of mailer identifying name

[davwheat]

This is my first contribution to this project. Sorry if I've missed out some steps (please go easy on me!).

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The name attribute for nodemailer allows the mailer to provide an optional identifying hostname to the SMTP server.

This is required for Google Workspace users wanting to use Google's Gmail SMTP relay service. Without this, Google will immediately reject the connection to its SMTP server with a very helpful message referring to denial of service.

Ref: https://community.nodebb.org/post/81300

I'm not sure where to submit English translations -- hopefully someone can point me in the right direction! 🤞

I intend for something like the following:

smtpName: SMTP identifying hostname
smtpNameHint: An optional name to send to the SMTP server to identify your mailer. For Google Workspace customers, this should be your main domain name.

[NGPixel]

Great first PR! Thanks!

I'll add the 2 strings to Lokalise.

[davwheat]

Thanks! 😄