Email validation throughout the Logi+ app incorrectly rejects valid subaddressed emails as invalid.

Email subaddressing is supported by most major email providers including Gmail, Outlook and iCloud. These are emails that look like username+tag1+tag2@example.com where emails reach username@example.com but are "tagged" with the content after the separator (normally a "+" symbol). Wikipedia's "Email Address" page has a good summary of supporting services and which character they use.