Yes, I'd first try not bouncing emails, sometimes this can interfere with the delete if bounce fails for any reason.... .. although you can still bounce in the 7.xx versions, (just right click an email and click mark for bounce), we disabled the bounce column and the automatic bounce option to stop users from bouncing all spam emails, as we no longer actually recommend to bounce all emails because 90% of all email addresses in Spam messages are forged and therefore no one will ever receive that bounce message and it is just unnecessary email traffic.
Plus, a lot of ISP's actively block bounces now, and sometimes even block the senders of these...
Where the bounce feature is demonstrably useful is where you are trying to get off a legitimate business's mailing list that you are having trouble opting out of. Business mailing lists usually do check for bounces, do recognize MailWasher bounces as legitimate and do remove you from their mailing list.
If no better, try these options...... for the account/s that has problems, (NOTE: first option is for POP type accounts only) disable pipelining under Settings>>Email Accounts, click your account, click Incoming>>Advanced, and uncheck both, PIPELINING options.
If this does not help, (or this is an IMAP account) can you please try deleting the problem email account and re-importing it.
Please open Mailwasher Pro and click, Settings>>Accounts, click your account and click, "Remove Account", click, "Yes, remove it", close and restart Mailwasher Pro.
In Mailwasher Pro click, Settings>>Accounts "Import Account" and follow the directions.
If there are no amounts listed, cancel to exit this screen and click, Add Account, choose your account type and add account manually.
Full directions are available for this from here:
Mailwasher Pro >> Help >> Help Topics >> Settings Screen >> Accounts
Most ISP's mail settings can be found by entering your email address here:
http://www.emailsettings.email/
Please let me know how you get on there.