Bounce management fails to mark Leads or Contacts as bounced or invalid

Currently, we set the email address as invalid for "user unknown" and other known user errors that our application receives from the intended recipients' mail server. This means that we have contacted the MTA (Message Transfer Agent) that owns the domain, presented the recipient to them and they have rejected it with a 5xx error that amounts to user unknown. If we get any other error messages that are not listed below the email may not be marked as invalid. If we do not receive any bounces from customer's side (their MTA) Salesforce will not mark the Emails as bounced or invalid.

The main replies from an MTA that trigger the bounce alert are:

• account has been disabled
• account inactive
• account is inactive
• account is not active
• account is not exist
• account not found
• account unavailable
• account unknown
• address could not be found
• address doesn't exist
• address invalid
• address is invalid
• address is not valid
• address is unknown
• address no longer exists
• address not found
• address not in valid
• address not known
• address not present
• address not valid
• address rejected
• address unavailable
• address unknown
• address you used is incorrect
• addressee unknown
• addresses are not valid
• addresses rejected
• account that you tried to reach is inactive
• bad address
• bad destination
• bad rcpt to
• bad recipient
• couldn't find that mail user
• does not exist
• domain lookup failed
• email address is no longer valid
• email is not valid
• email recipient specified is incorrect
• inactive email address
• inactive user
• incorrect address
• incorrect email address
• invalid account
• invalid address
• invalid e-mail
• invalid email
• invalid mailbox
• invalid rcpt
• invalid recipient
• invalid user
• invalid-email-address
• mailbox invalid
• mailbox is not available
• mailbox not found
• mailbox unavailable
• mailbox unknown
• no longer active
• no longer at this address
• no longer on server
• no mail box available
• no mailbox by that name
• no mailbox found
• no mailbox here
• no such account
• no such address
• no such e-mail address
• no such email
• no such local recipient
• no such local user
• no such mailbox
• no such person
• no such recipient
• no such student
• no such user
• no user at this address
• no user here by that name
• no valid recipient
• non-existent email address
• non-existent recipient
• non-existent user
• non-valid addressee
• nonexistent account
• nonexistent local account
• nonexistent user
• nosuch address
• not a known user
• not a valid email address
• not a valid mailbox
• not a valid user
• not found on our mail servers
• not found recipient
• not known here
• not our customer
• not stored this user
• rcpt is not available
• rcptto is invalid
• recipient cannot be verified
• recipient invalid
• recipient is in my bad
• recipient is not exist
• recipient is not in
• recipient not exists
• recipient not found
• recipient rejected
• recipient unavailable
• recipient unknown
• rejected recipient
• t in my list of allowed recipients
• this user doesn
• unavailable mail user
• unknown account
• unknown address
• unknown e-mail address
• unknown email address
• unknown local recipient
• unknown local-part
• unknown mailbox
• unknown or illegal alias
• unknown recipient
• unknown user
• unkown user
• user disabled
• user doesn't exist
• user invalid
• user is inactive
• user is unknown
• user no found
• user not exist
• user not found
• user not known
• user unknown
• username unknown
• userunknown

Note: For more information on Bounce Management, see Enable Email Bounce Handling

For Bounce Alerts related to Workflows, see Workflow Rule: Email Alert Does Not Utilize Bounce Management Address