Hello,

We work with a DT85M, firmware v9.16, used to send emails with SMTP.

I used dEX to configure the system:
-- Modem email --
From Name: daq
email: xxxxxx@gmx.com
SMTP port: 25
SMTP server: smtp.gmx.com ( I also tried mail.gmx.com)
Username: xxxxxx@gmx.com
Password: xxxxxx
-- Modem --
APN (manual): epc.tmobile.com (the carrier is T-mobile)
Username: [blank]
Password: [blank]

Problem:
When the system tries to send email, generally it does not work.
Sometimes it works, but after sending few emails, there is a fail (after the first fail, it will never work again, we have to toggle (turn off/turn on) the system to try another time)

Environment:

• on the system, the network seems to work properly: we see the carrier (T-mobile), the "E" for Edge, the good reception, and the IP address.
• we have a good and stable GSM reception: 60 to 80dBm.
• the antenna is working properly (same problem with a spare antenna).
• the SIM is working properly

Extract of the diagnosis when it fails:
Unloading: CONFIG B Data (2 records) -> mailto:xxxxxx@gmx.com (002_19890102T031700.CSV)
EMAIL: Connecting to server (smtp.gmx.com:25)
Unload complete.
EMAIL: Sending to xxxxxx@gmx.com (B:\UNLOAD\002_19890102T031700.CSV)
EMAIL: Failed - will retry

Reason of this problem:

• Could it be a IMEI problem ?
• The BER (bit error rate) is around 10% when the system sends something. Why, and could it be the reason of the problem ?
• Is it because we should use a DynDNS ?
• SMTP server which does not work properly ?
• Hardware problem in the modem ?
• VLITH (Internal Lithium memory-backup battery voltage) is 1.50V according to the self test, it should be around 3.6V. Could it explain the problem ?

I worked a long time on that problem and I cannot figure out the root cause.
Thank you in advance for your help

For your information, I tried the DT56=8 command in the command windows to see the details about the SMTP communication.
The 13 first emails have been sent well, then the fourteenth failed. After that, every try fails.

The result is below (we can see that the 13th try succeeds, then the 14th time fails):
EMAIL: Connecting to server (mail.gmx.com:25)
Unload complete.
SMTP << 220 gmx.com (mrgmx103) Nemesis ESMTP Service ready
SMTP >> EHLO [192.168.111.111]
SMTP << 250-gmx.com Hello [192.168.111.111] [172.56.2.200]
250-SIZE 69920427
250-AUTH LOGIN PLAIN
250 STARTTLS
SMTP >> AUTH LOGIN
SMTP << 334 VXNlcm5hbWU6
SMTP << 334 UGFzc3dvcmQ6
EMAIL: Sending to david.riff@consultant.volvo.com,volvotrucksdaq3@gmx.com (B:\UNLOAD\008_19890101T011400.CSV)
SMTP >> MAIL FROM: volvotrucksdaq@gmx.com
SMTP << 235 Authentication succeeded
SMTP >> RCPT TO: david.riff@consultant.volvo.com
SMTP << 250 Requested mail action okay, completed
SMTP >> RCPT TO: volvotrucksdaq3@gmx.com
SMTP << 250 OK
SMTP >> DATA
SMTP << 250 OK
SMTP >> Subject: 19890101T011400
MIME-version: 1.0
From: "volvotrucksdaq" volvotrucksdaq@gmx.com
To: david.riff@consultant.volvo.com, volvotrucksdaq3@gmx.com
SMTP >> Content-Type: multipart/mixed; boundary="g4hd62ngJ2e00B"

This is a multi-part message in MIME format.

--g4hd62ngJ2e00B
Content-Type: text/plain; charset=us-ascii
Content-Transfer-Encoding: 7BIT

SMTP >>

--g4hd62ngJ2e00B
Content-Type: text/plain
Content-Transfer-Encoding: 7BIT
Content-Disposition: attachment; filename="008_19890101T011400.CSV"

SMTP >>
--g4hd62ngJ2e00B--SMTP >>
.
SMTP << 354 Start mail input; end with <CRLF>.<CRLF>
SMTP << 250 Requested mail action okay, completed: id=0LqQTl-1cawqP22q1-00e6rb
EMAIL: Sent OK
SMTP >> QUIT
SMTP << 221 gmx.com Service closing transmission channel
T_ENOW OverRange degC
T_MIDSUMMER OverRange degC
T_ref 25.2 degC

Unloading: CONFIG B Data (1 records) -> mailto:david.riff@consultant.volvo.com,volvotrucksdaq3@gmx.com (009_19890101T011500.CSV)
EMAIL: Connecting to server (mail.gmx.com:25)
Unload complete.
SMTP << 220 gmx.com (mrgmx102) Nemesis ESMTP Service ready
SMTP >> EHLO [192.168.111.111]
SMTP << 250-gmx.com Hello [192.168.111.111] [208.54.35.159]
250-SIZE 69920427
250-AUTH LOGIN PLAIN
250 STARTTLS
SMTP >> AUTH LOGIN
SMTP << 334 VXNlcm5hbWU6
SMTP << 334 UGFzc3dvcmQ6
EMAIL: Sending to david.riff@consultant.volvo.com,volvotrucksdaq3@gmx.com (B:\UNLOAD\009_19890101T011500.CSV)
SMTP >> MAIL FROM: volvotrucksdaq@gmx.com
SMTP << 235 Authentication succeeded
SMTP >> RCPT TO: david.riff@consultant.volvo.com
SMTP << 250 Requested mail action okay, completed
SMTP >> RCPT TO: volvotrucksdaq3@gmx.com
SMTP << 550-Requested action not taken: mailbox unavailable
550 Failure sending mail. Try again later
SMTP >> QUIT
SMTP << 550-Requested action not taken: mailbox unavailable
550 Failure sending mail. Try again later
EMAIL: Failed - will retry

We can see that the IP address is changing. However, it was already changing for the 11th and 12th.

Hi David,

That error may appear when:

• due to some error in the system, SMTP server could not find david.riff inbox
• david.riff inbox is full
• repeatable email is being treated as a spam thus the domain locked itself for new delivery (from the same sender)

Looking at the script (continuous email transfer every minute?) and the number of success delivery (13). I believe the third option applies in your case.
Please try to use longer interval, or set volvotrucksdaq into white list of mail.gmx.com

Best regards,
Rudy Gunawan

Hi Rudy,

On GMX, I put my email address in the whitelist, and I tried to do the same test by sending an email every hour. I still have the same problem.
It stops after a while.
Do you have other ideas about what could be the root cause ?

Best regards
David RIFF

Hi David,

Please try to use an external SMTP server such as SMTP2GO to narrow down the possibility of causes.
If the external server is OK then there could be some setting in your mail server that restrict multiple receiving (from the same address).

Is it possible that your mail.gmx.com was being hosted by another application (i.e.: google Apps)?

Best regards,
Rudy Gunawan

Hello,

"- repeatable email is being treated as a spam thus the domain locked itself for new delivery (from the same sender)"
FYI, after increase the period between 2 emails, we never had problems.
So you were right, the communication was seen as a potential spam and blocked when sent too often.

David