Error when adding to dependencies

[Poreis]

First thank you for this awesome library!
So I have done everything like you say but I get this error :

error: dependency 'SwiftSMTP' in target 'Resumos.nosync' requires explicit declaration; provide the name of the package dependency with '.package(name: "SwiftSMTP", url: "https://github.com/IBM-Swift/Swift-SMTP", .upToNextMinor("5.1.0"))' and now I can't install it

[sanzaru]

Maybe a bit late, but:

Try to specify a name for the package inside your Package.swift:

dependencies: [
    .package(name: "SwiftSMTP", url: "https://github.com/Kitura/Swift-SMTP", .upToNextMinor(from: "5.1.0")),
],

After specifying the name I could run swift build without problems.