1. End-user cannot send mail.
2. When sending, end users get a pop-up error message OR users get a bounce message
Some common causes
1. Recipient id not present or has been disabled.
(The bounce mail or the pop-up alert will have a message saying one or more recipient addresses is invalid.)
2. Sender IP has failed the reputation check.
3. The user has crossed the max recipients count.
4. The user has exceeded the daily limit on the number of mail that can be sent and further mail sending for the user has been blocked.
( The bounce mail or pop-up alert will have the following message: 553 sorry, your mail was administratively denied)
Case 1: Recipient id not present or disabled
Verify the email id entered in the recipient's list is valid. Re-send email to a valid id.
Case 2: Sender IP has failed the reputation check
Raise a ticket with Mithi to add the IP to the whitelist to bypass reputation-based filtering.
Case 3: User has crossed the max recipients' count
Users are allowed to send an email to max 200 recipients. Ask the user to reduce the recipients and resend the mail.
Case 4:The user has exceeded the daily limit on the number of mail that can be sent and further mail sending for the user has been blocked.
a. If the user has not been sending out the additional mail, then the user's PC may be compromised and has been infected with a certain type of virus such that the PC has become a spam generation agent. (The virus hijacks the desktop mail client (typically MS Outlook) and pumps large volumes of mail to the configured outbound SMTP server using the authentication information remembered in the mail client. All this typically happens without the user's knowledge.)
Make sure the PC on which the user's email account has been configured is not compromised. Update the antivirus. Once you have confirmed that the PC has been cleaned, raise a ticket with Mithi to remove the ID from the blacklist.
b. If the PC was not compromised and the default sending limit has to be increased for the user, raise a ticket with Mithi. As mentioned in the SLA, every domain can have a limited set of power users with a higher limit. The team will check your domain status and update the limits.
There may be more reasons why the user could not send the mail. For these reasons, please attach the screenshot of the pop or attach the bounce message so that the Mithi team can analyze the cause.