Duplicate checking when adding email to personalization is not accurate

[tmimura39]

Issue Summary

About the duplicate check added by https://github.com/sendgrid/sendgrid-ruby/pull/437 It's not accurate to be case insensitive.

Steps to Reproduce

1. Add uppercase email
2. Add duplicate uppercase email
3. No DuplicatePersonalizationError occurs
4. Request processing runs and 400 is returned

[childish-sambino]

This issue has been added to our internal backlog to be prioritized. Pull requests and +1s on the issue summary will help it move up the backlog.

[clinejj]

A suggested improvement could be to manually de-duplicate rather than raising an error. The python and C# libraries are adding this functionality: https://github.com/sendgrid/sendgrid-python/issues/788 https://github.com/sendgrid/sendgrid-csharp/pull/991

(I admittedly didn't know that SendGrid would bounce an email back and am receiving this error, when I would rather just have the duplicates removed and the email sent)

[netwire88]

I also have the same problem, if the same email address is in to and cc, then SendGrid::DuplicatePersonalizationError is raised.

[netwire88]

@JenniferMah Hi, I'm using the latest build and having issues with 2 related scenarios:

1. upper vs. lower case - if I have test1@example.com and TEST1@EXAMPLE.COM, that doesn't work
2. to/cc/bcc fields - if I have test1@example.com in to field and cc field, then it doesn't work. Similarly with to and bcc, and cc & bcc

[JenniferMah]

Hi @netwire88 Could you please open a new issue with this information?

[netwire88]

Sure