This Ever Happen To You?

DaisyDay said:

This has not happened to me, but one possibility is that she accidentally flagged your email as "junk" or someone from the same domain as you was flagged.

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Sketcher said:

You might have a bad neighbor on your mail server. The way e-mail works, every e-mail address on the same domain name sends from the same IP address, and multiple domains will often send mail from the same IP address. Therefore, if any one of those e-mail addresses sends spam and gets caught, the sending IP could get blacklisted by the receiving server.

You should contact your host about this. Provide the sending address, the intended receiving address, and the time you sent the message. They may also want a copy of the bounceback that you have received.

Ways to protect yourself from this:

1) Make sure all computers and mobile devices are regularly scanned for viruses and malware, with the scanners and their signatures kept up-to-date.
2) Only use encrypted connections to log into your e-mail account. That means either STARTTLS or SSL/TLS when connecting to the mailserver for both sending and receiving. Ask your host for details on this.
3) Use long, hard-to-guess passwords that are easy to remember. Avoid keywords that can be traced back to you, your family, your interests, or your business. Nonsensical phrases that you will never forget nor say in public are a good choice. Go for 16 characters or more, it is exponentially harder to crack a 16 character password than an 8 character password.
4) If you have a website with a mail form, make sure it is also kept up-to-date, and make sure the mail form has a strong recaptcha script if it is in any way public facing - even if it is only supposed to send back to you.
5) If you forward mail, use a server-side spam filter so it at least gets marked before it is forwarded. Otherwise, since it was forwarded from your server, your server will get blamed for spamming.
6) Make sure that your mailbox quota or server disk quota is not full. Full mailboxes bounce e-mails back at the senders, with an indication that the mailbox was full. The problem is, servers look at message contents now and if there's spam in the message that got bounced back, your server will get blamed for bouncing it back.
7) If you use BoxTrapper at all, stop using it. Similar to the full mailbox issue, BoxTrapper sends a copy of the message back to the sender to verify that the sender is human. Problem is, if it is spam, then the server that receives the copy looks at that message coming in, sees the spammy content, and blocks mail from your server. This is particularly bad for you if they are sending from a compromised Yahoo, Hotmail, or GMail account, or any other large mail provider.
8) If everybody in your organization that has an e-mail account diligently abides by these, consider paying extra for your own sending IP, or making use of an external premium mail service while keeping the web host the same.

Fighting spam on the Internet is literally part of what I have been doing for a living for the last several years, and I have seen my share of issues that occurred because of the first 7 reasons above. Don't do 8 without minding the first 7.

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