trying to send mail with golang

here's my code:
package main

import (
    "fmt"
    "log"
    "net/http"
    "text/template"
    "github.com/gopkg.in/gomail.v2"
)

var tpl *template.Template

type pageData struct {
    Title    string
    subject string
    email    string
    msg      string
}

func init() {
    tpl = template.Must(template.ParseGlob("templates/*.gohtml"))
}

func main() {
    fmt.Println("server running")
    http.HandleFunc("/", index)
    http.HandleFunc("/about", about)
    http.HandleFunc("/contact", contact)
    http.HandleFunc("/apply", apply)
    http.Handle("/favicon.ico", http.NotFoundHandler())
    http.ListenAndServe(":8080", nil)
}

func index(w http.ResponseWriter, req *http.Request) {

    pd := pageData{
        Title: "Welcome || CACCYE",
    }
    err := tpl.ExecuteTemplate(w, "index.gohtml", pd)
    if err != nil {
        log.Println("LOGGED", err)
        http.Error(w, "internal server error", http.StatusInternalServerError)
        return //if you return a function you're done with that function. execution never reaches the next line.
    }
    //fmt.Println(req.URL.Path)
    //fmt.Println("We got here")
}

func about(w http.ResponseWriter, req *http.Request) {

    pd := pageData{
        Title: "about || CACCYE",
    }
    err := tpl.ExecuteTemplate(w, "index.gohtml", pd)
    if err != nil {
        log.Println(err)
    }
}

func contact(w http.ResponseWriter, req *http.Request) {
    var s string
    var e string
    var m string
    pd := pageData{
        Title: "contact || CACCYE",
    }
    if req.Method == http.MethodPost {
        s = req.FormValue("subject")
        e = req.FormValue("mail")
        m = req.FormValue("message")

        pd.subject = s
        pd.email = e
        pd.msg = m

        cb := gomail.NewMessage()
        cb.SetHeader("From", e)
        cb.SetHeader("To", "person1.mail@gmail.com", "person2.mail@gmail.com")
        cb.SetHeader("Subject", s)
        cb.SetBody("text/plain", m)

        d := gomail.NewDialer("smtp.gmail.com", 465, "my_mail@gmail.com", "my_password")

        // Send the email to Bob, Cora and Dan.
        if err := d.DialAndSend(cb); err != nil {
            panic(err)
        }
    }

    err := tpl.ExecuteTemplate(w, "contact.gohtml", pd)
    if err != nil {
        log.Println(err)
    }
}

and here's what my terminal outputs after clicking submit:

2017/06/01 19:57:55 http: panic serving [::1]:51538: 534 5.7.14 <https://accounts.google.com/signin/continue?sarp=1&scc=1&plt=AKgnsbvq
5.7.14 fwf1FzvpYX6fjLJA3C7wfQxFi7Tn5hY4Kfw3-jfTn-W0UQoeh4u-zUkuWCzmCxuEa9KBu2
5.7.14 r1BPMJdj0VIHxr3Pjw1pBLAWlTfDuy5g7OH0W2CwVIxrW2LcHs2U0-whzjOMkNiRhyPETy
5.7.14 lztVmXqiS3mGZXhTGKg5t8JJN_rL3niVt3wardvEgEQkKhOiOGtGLATNwf2yTRVrjs1iw1
5.7.14 z-yuIhLO4tX7K8y360uELPeFvzXwo> Please log in via your web browser and
5.7.14 then try again.
5.7.14  Learn more at
5.7.14  https://support.google.com/mail/answer/78754 d2sm11201710ede.31 - gsmtp
goroutine 6 [running]:
net/http.(*conn).serve.func1(0xc42008c6e0)
    /usr/local/go/src/net/http/server.go:1721 +0xd0
panic(0x6fb7a0, 0xc420436680)
    /usr/local/go/src/runtime/panic.go:489 +0x2cf
main.contact(0x8b6740, 0xc4201382a0, 0xc420100900)
    /home/connelblaze/go/src/github.com/connelevalsam/GoWebDev/001/src/sendmail/src/main/main.go:86 +0x5d3
net/http.HandlerFunc.ServeHTTP(0x769658, 0x8b6740, 0xc4201382a0, 0xc420100900)
    /usr/local/go/src/net/http/server.go:1942 +0x44
net/http.(*ServeMux).ServeHTTP(0x8e38e0, 0x8b6740, 0xc4201382a0, 0xc420100900)
    /usr/local/go/src/net/http/server.go:2238 +0x130
net/http.serverHandler.ServeHTTP(0xc42011e0b0, 0x8b6740, 0xc4201382a0, 0xc420100900)
    /usr/local/go/src/net/http/server.go:2568 +0x92
net/http.(*conn).serve(0xc42008c6e0, 0x8b6d40, 0xc420018680)
    /usr/local/go/src/net/http/server.go:1825 +0x612
created by net/http.(*Server).Serve
    /usr/local/go/src/net/http/server.go:2668 +0x2ce
2017/06/01 19:57:58 http: panic serving [::1]:51554: 534 5.7.14 <https://accounts.google.com/signin/continue?sarp=1&scc=1&plt=AKgnsbvd
5.7.14 kK4tr3ffn3kjLRKeeP-wAkXO93J6KwJVC0KLX7_AJo0P1ewxeRL4pT7x9fsztrCIoqEv_l
5.7.14 L6qWkwT1cswhb3yWNeFQyoWTb2NTwhlL-6dJ6guZhdUuTrg4e554IQqm0wHSuIeqcbtx2b
5.7.14 g9mnmRTsOhM_4EoiCfxH1fSEuYHTqP7hvk50vgWGBTtdsn-4OxSUUS2NFCbWuAA0ZKWjLl
5.7.14 odn5w9XGMsCw4722cZ3ClFqXtYGmg> Please log in via your web browser and
5.7.14 then try again.
5.7.14  Learn more at
5.7.14  https://support.google.com/mail/answer/78754 r18sm9842448edd.23 - gsmtp
goroutine 25 [running]:
net/http.(*conn).serve.func1(0xc4201aa000)
    /usr/local/go/src/net/http/server.go:1721 +0xd0
panic(0x6fb7a0, 0xc420163a60)
    /usr/local/go/src/runtime/panic.go:489 +0x2cf
main.contact(0x8b6740, 0xc420138540, 0xc420101400)
    /home/connelblaze/go/src/github.com/connelevalsam/GoWebDev/001/src/sendmail/src/main/main.go:86 +0x5d3
net/http.HandlerFunc.ServeHTTP(0x769658, 0x8b6740, 0xc420138540, 0xc420101400)
    /usr/local/go/src/net/http/server.go:1942 +0x44
net/http.(*ServeMux).ServeHTTP(0x8e38e0, 0x8b6740, 0xc420138540, 0xc420101400)
    /usr/local/go/src/net/http/server.go:2238 +0x130
net/http.serverHandler.ServeHTTP(0xc42011e0b0, 0x8b6740, 0xc420138540, 0xc420101400)
    /usr/local/go/src/net/http/server.go:2568 +0x92
net/http.(*conn).serve(0xc4201aa000, 0x8b6d40, 0xc42040d580)
    /usr/local/go/src/net/http/server.go:1825 +0x612
created by net/http.(*Server).Serve
    /usr/local/go/src/net/http/server.go:2668 +0x2ce