Sending many emails to invalid, challenging-bounced email addresses tells Gmail spam filters that you simply’re engaged in “spammy” things to do. Difficult bounces destruction your sender’s track record and shipping and delivery rates. Kensuke Nagae @kyanny I’ve experienced a hard time starting an SMTP server for a few tests https://itsupport22222.blogars.com/26337513/a-review-of-smtp-server