Gmail blocks backup mailbox

Question

Google

Good afternoon.
I have the following problem:
I wrote a bash script that mutt sends a daily database backup to google mail. from the [email protected] account to yourself.
The problem is that about once a week, mail is blocked, letters are not sent, and when you try to log in through the browser, it requires you to enter a captcha in addition to the password. Apparently blocked with suspicion of spam?

I would be very grateful to those who will tell you how to do everything right, in the style of "set it and forget it."

UPD:
I added information to the body of the letter, two weeks, the flight is normal. Now the email looks something like this:

Subject: Daily backup for 2013.10.18

MD5 hash: 6342850f40fa8bb7efa3696afb1b4f6d
File size: 6956kb
Filename: daily_backup_2013.10.18_03-05-01.tgz
Time: 03:05:01

I noticed another nuance - the server does not accept letters larger than 15 MB, despite the fact that the certificate claims a possible 25.

Answer 1

Fail2ban works correctly for me and sends messages without any mutt through the standard postfix in centos.
The only thing is to click not spam on these letters a couple of times and it is desirable to have a correct ptr record for the IP from which you send letters.

Answer 2

Apparently the base is small once by mail? Put Dropbox on a server and put backups there. It is possible any rsnapshot.

Answer 3

And at once to pour on gdrive will not go? Fortunately, there are a lot of third-party console utilities for working with it.

Answer 4

rechmp , please mark if the solution worked