fix: type validation on to_emails parameter on mail object

[DougCal]

Fixes #778

Validated values at runtime for a clearer error message for when someone sets to_emails to a list of lists

[eshanholtz]

Thanks for the PR! Everything looks good, but would you please add tests to verify no error is thrown with the list(tuple), list(str), str, and tuple formats, for completeness? Looks like all the other tests use To and list(To) formats.

[DougCal]

Tests are in @eshanholtz !

[eshanholtz]

LGTM! Thank you for the contribution :)

[honzajavorek]

This breaks my code, the type check now won't allow anything else than To:

Mail(to_emails=[To(job.email, job.company_name),
                Bcc('[email protected]', 'Honza')], ...)

Do I use to_emails in a wrong way or is it a regression?

[eshanholtz]

@honzajavorek

The original intention was for the to_emails to refer specifically to the "to" portion of the email, but testing locally shows that it properly rendered Cc and Bcc emails the way you were using it. I'll work on a fix to allow these recipient types and will release a new patch today. Thanks for pointing this out!

[honzajavorek]

@eshanholtz Thank you! What is the preferred way of doing this if this worked only by accident? Also, let me know if I can help with the fix.

[eshanholtz]

@honzajavorek I'd say the way you were doing it is a perfectly valid use of to_emails. The patch release to fix the break of this use case is version 6.4.3

[honzajavorek]

Awesome, thanks!