Custom SMTP Server fails sending emails with error "Local address contains control or whitespace"DescriptionWhile configuring a custom SMTP account, there are three essential fields: 1. Email user label - Name Displayed in Outgoing Email. 2. User Name - For SMTP Account, this field must contain full email address. The value entered in From field overrides this value. 3. From - Used in SMTP Account only. The Email Account from which the notification will be sent. This email address value can override to value entered in User name.CauseThe cause of the issue can be white space in the From address field. Make sure not to confuse the Email Address label and the From field. The From Field must contain the email address which is sending the email. The Email Address label field will be the descriptive name visible for the email account.ResolutionConfigure the correct email address in From and User Name fields, with display name to be configured in Email Address label field.Additional InformationEmails sent from custom SMTP email account ProofPoint are sometimes stuck in a send-retry loop Slow outbound email processing when own SMTP server is used Outbound emails are failing with invalid addresses blocked by Spamhaus with custom configured SMTP Server