Email send error

CReborn said:

Hello everybody.

Since a week ago, my phone stopped sending emails. No matter the app (I'm using k9 for years), I get the "no valid recipient" error. All the server settings are correct, and unchanged. What is wrong?

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Well, honestly, if your Internet is working properly, then something did change... Whether it is server side or somewhere else, something is different. The phone itself is not the issue, as email is handled by the application, not the phone. You could always test it in Safe Mode, or perform a factory default to double check if you wish.

The fact that you state that multiple apps have this issue, leads me to believe that something has changed server side. I would check with your email service provider.

I have been using Nine Mail from 9folders for some time, using multiple business accounts talking to Exchange, and Gmail with 3 personal accounts and I can send/receive on all of them with zero issues.

CReborn said:

I can't enter safe mode. When I get the power off screen, and press it, it doesn't give me the option to reboot in safe mode.. it just shuts down...I have contacted my ISP.. they are playing stoopid.. so I've sent an email to their tech support.. and I'm waiting for an answer

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Pretty sure I was replying in the official forums and my postings got erased.

Safe mode is pretty easy, press and hold the power button on the side of the phone until the "Power Off" button shows on the screen, then release the power button on the side of the device. In one motion, press your finger on the on-screen Power Off button and hold it down (don't move or tap it) for about 2-3 seconds and the Safe Mode window should appear.

Honestly though, this isn't likely to get you the answer... In the Moto thread you stated you were getting this error:

Error: 554 5.7.1 <93-139-143-51.adsl.net.t-com.hr[93.139.143.51]>: Client host rejected: Access denied

This is actually all the information needed... Getting to "Error 554" requires that your email client connected to the mail server, authenticated and sent the destination address, and was denied. The interesting part is "Client host rejected: Access denied", and although email servers can vary, this is a response when your email client or device is not allowed and actively blocked (like they are blocking Android devices, or Moto G5+ devices, which would be extremely odd).

Cause
SMTP Code 554. 5.7.1 is basically a rejection from the Recipient Domain. SMTP Code 554. 5.7.1 means 'Not allowed'. The address in MAIL FROM appears to have insufficient submission rights, or is invalid, or is not authorized with the authentication used; the address in a RCPT TO command is inconsistent with the permissions given to the user; the message data is rejected based on the submitting user.

The other possibility is that:

1) The authentication method your email client is using is not correct, or invalid for the source IP address
2) Your email account does not have sufficient permissions to send to the recipient from your device or IP address
3) The recipient address is blocked/forbidden on the email server
4) The data of the message is not allowed for your account permission level

#3 & #4 would be very unusual... #1 is the most common.

Since the EXACT same setup works on a PC's email client, can you connect via WiFi to the same network the PC is using with the phone and try to send (verify your local IP address is in the same subnet and your public IP is the same), does this work? If it does, the issue is your mail service provider likely needs a different authentication method for "off-net" email, common with many ISP's. If it still doesn't work, then this goes clearly back to your mail service provider and you should contact them and get your issue escalated to a higher level of support.

Is this a commercial email service (like Hotmail, Yahoo, Office365, or something else), an email address hosted by your ISP (your Internet Service Provider is CableCompany and your email is user@cablecomp.net or similar), or a corporate email?

Login to your email on a PC and see what happens. Change your password, then install an email app on your phone.