fix: fail email sending if email address is empty

[hf]

Sad but true. Empty email address "send" was considered successful.

[coveralls]

Pull Request Test Coverage Report for Build 17242085652

Details

• 3 of 14 (21.43%) changed or added relevant lines in 3 files are covered.
• 1 unchanged line in 1 file lost coverage.
• Overall coverage decreased (-0.05%) to 70.753%

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Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
internal/api/external.go	0	3	0.0%
internal/api/identity.go	0	4	0.0%
internal/api/mail.go	3	7	42.86%

Files with Coverage Reduction	New Missed Lines	%
internal/api/external.go	1	75.9%

Totals
Change from base Build 17191439812:	-0.05%
Covered Lines:	12270
Relevant Lines:	17342

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💛 - Coveralls

[cstockton]

Nice catch, looks good to me. 👍

[hf]

Keeping this for the next release.