Not within QB
You could ask for them to print it, sign it, scan it and return it as an attachment, or
Have them respond by email quoting the estimate number, date, and amount and telling you it is approved, or
The net has several electronic signature services,like
Resolution for 'Can customers sign issue: 'Can customers sign an estimate through email?' available: Yes.
The Can customers sign issue or error code is a known issue in Quickbooks Online (QBO) and/or Quickbooks. Support for this issue is available either by self-service or paid support options. Experts are available to resolve your Quickbooks issue to ensure minimal downtime and continue running your business. First try to resolve the Can customers sign issue yourself by looking for a resolution described in the article. If it is a complex Can customers sign issue or you are unable to solve the issue, you may contact us by clicking here or by using other Can customers sign support options.
For more information about resolving issues related to Can customers sign in Quickbooks/QBO or to get support for the issue 'Can customers sign an estimate through email?', click the link below: