Set to field when using merge_data

[lewistaylor]

The to field is required even if providing recipient addresses in x-smtpapi. See https://sendgrid.com/docs/API_Reference/Web_API/mail.html#-send.

[lewistaylor]

Please note I'm stacked with another project and haven't added any regression tests for it.

Update: Just decided to modify the test.

[medmunds]

Thanks for this.

I'm a little confused by SendGrid's docs on this. As you point out, to is required and "Must be a valid email address." But:

Note that recipients passed in this parameter will be visible as part of the message. If you wish to hide the recipients, use the TO parameter in the x-smtpapi header.

With merge_data (batch send), we definitely want to hide the recipients from each other. If you provide both to and x-smtpapi to, do all the recipients see the full to list?

[medmunds]

If you provide both to and x-smtpapi to, do all the recipients see the full to list?

OK, quick test answered my own question: with both to params set, SendGrid does not make all the recipients visible to each other.

Thanks for the fix. I'll add an integration test for this, too.

[avelis]

@medmunds I had a chance to talk to SendGrid support on this awhile back. The x-smtpapi to field will not show all the recipients emails to each other. The regular to field will.

When using the x-smtpapi to field the regular to field will be ignored. Therefore they suggested adding the from email as the to in this specific scenario.

I do agree that the SendGrid docs could make this clearer.

[lewistaylor]

@avelis @medmunds I'll update the code and tests later today

[medmunds]

@avelis thanks- that's helpful to know. Using from as to is probably a good safety mechanism to avoid accidentally exposing all the real to emails if something went wrong with smtpapi.

@lewistaylor I already released your PR (with a couple of tweaks) as 0.3.1. You may need to rebase before updating this PR. (Or just submit a new one if that's easier.)