Question: In Gmail, I created a personal folder to save received emails for future reference. But Gmail removes them from this folder after a month or less. Where did these emails go, and how can I keep them? — J.W, Suffield, Conn.

Answer: There are many possible sources of the problem. But one of the main causes is a misunderstanding of how Gmail operates.

To look at the Gmail screen, you would think that you had at least two copies of every message. There’s one in the inbox and there’s another one in the “all mail” folder. But that’s an illusion. Gmail has only one copy of each email, and it resides in the “all mail” folder. If that email is deleted, it’s sent to the trash folder, from which it will be permanently erased after 30 days.

So, let’s say you want to keep an email. You drag it from the inbox to your personal folder. This causes the email to appear in the personal folder and to disappear from the inbox (this is accomplished by “labels” that Gmail uses to make emails appear to be in different folders.) Stop there. Don’t delete any “duplicate copies” of the email because there aren’t any — there’s only the original that stays in “all mail.”

Something similar happens with group emails, in which people respond to an email you sent. Both the original email and the responses are grouped together as one email that resides in “all mail.” If you delete the original email or one of the responses, the whole chain of messages is sent from “all mail” to the trash folder.

What are the other potential causes of email loss in Gmail?

• Your account might have been hacked. If that’s the case, change your password and check Gmail’s settings for tampering (See “Securing your account” at tinyurl.com/4nh5zws9).
• If you use a computer-based mail program such as Microsoft Outlook or Mozilla Thunderbird, emails might have been deleted from the mail server once you downloaded them to the mail program. Changing mail program settings can fix this.
• You might have created an email filter that automatically archives or deletes some emails. These filters can be changed to fix the problem. If you can remember the words in these emails, you can search all of Gmail in hopes of finding any messages that were archived.
• If your Gmail automatically forwards emails to another email account, the original Gmail message might be deleted unless Gmail’s settings are adjusted to keep a copy.
• See tinyurl.com/4e5tkswf to fix these problems or to ask Google to help recover lost mail.

Question: Many of my friends are using texting instead of email, but I don’t have a smartphone. Is there a way I can use a desktop or laptop computer to send and receive text messages? — M.K., Lindstrom, Minn.

Answer: You can send and receive text messages through your email account, although it’s slower than with phone-to-phone texting. Address the email to the person’s mobile phone number followed by the cellular carrier’s email suffix. For example, to send a text message to the Verizon Wireless phone number 612-xxx-yyyy, use the email address 612xxxyyyy@vtext.com (or, if your text message includes a photo, use 612xxxyyyy@vzwpix.com). (For the email suffixes of other cellphone companies, see tinyurl.com/95ek9sp5).