Panic when MX record is empty

[daffarg]

checkmail/checkmail.go

Line 64 in dfb1781

client, err := DialTimeout(fmt.Sprintf("%s:%d", mx[0].Host, 25), forceDisconnectAfter)

I just tested with random host name, for example like invalidmail.com. The LookupMX function does not return an error, but the MX record is empty. So, it will panic on line 64 when accessing the first index of empty MX record. I think it's better to check the length of MX record first.